after adding UNION ALL clause ,column value unexpectedly change

## Bug Report

Please answer these questions before submitting your issue. Thanks!

### 1. Minimal reproduce step (Required)
```SQL
DROP DATABASE IF EXISTS test;
CREATE DATABASE IF NOT EXISTS test;
USE test;
CREATE TABLE t1 (
c1 INT NOT NULL AUTO_INCREMENT,
c2 VARCHAR(255) NOT NULL,
c3 VARCHAR(255) NULL,
c4 INT NULL,
c5 DATE NOT NULL,
c6 VARCHAR(10) NOT NULL,
PRIMARY KEY (c1)
);

CREATE TABLE t3 (
c1 INT NOT NULL AUTO_INCREMENT,
c2 INT NOT NULL,
c3 INT NOT NULL,
c4 YEAR NOT NULL,
c5 TIME NULL,
c6 TINYINT NULL,
c7 SMALLINT NULL,
c8 MEDIUMINT NULL,
c9 BIGINT NULL,
c10 LONGTEXT NULL,
c11 VARCHAR(255) NULL,
c12 TINYTEXT NULL,
c13 TINYBLOB NULL,
c14 SET('x','y','z') NULL,
c15 TINYINT(1) NULL,
PRIMARY KEY (c1)
);

INSERT INTO t1 (c1, c2, c3, c4, c5, c6) VALUES (3584, 'sample_AQJP3FCb7PX46hF2d3VoKsPIHtIgzieVgOK1Ue7iSbNProjjh', 'sample_v', 36, '2025-09-07', 'sample_J');
INSERT INTO t1 (c1, c2, c3, c4, c5, c6) VALUES (954, 'sample_0kfPnPKeUjkycwqHxj5OtQ8', 'sample_sQ', 90, '2025-10-10', 'sample_C');

INSERT INTO t3 (c1, c2, c3, c4, c5, c6, c7, c8, c9, c10, c11, c12, c13, c14, c15) VALUES (8417, 9828, 4869, 2023, '2023-01-01 21:39:34', 14, 68, 41, 89, 'sample_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', 'sample_weZoLCxaYRuEbIZSAcw', 'sample_8eD325FzN79CIA1lx3hcxnIVFhKIlbppGhso8TzRvfqzVgovF4texBWt2e15D4TE8uXMELQHhSBEC2wHYIIOfKH8XCNMYbzkX06yuiY1u41mec1TesgBYKV3PW', X'D2A6D881052BECAA90E6BDA5DBAF542830D084', 'y,z', NULL);
INSERT INTO t3 (c1, c2, c3, c4, c5, c6, c7, c8, c9, c10, c11, c12, c13, c14, c15) VALUES (4582, 4362, 2120, 2003, '2023-01-01 10:35:52', 75, 23, 4, 15, 'sample_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', 'sample_OMHD5WHEEeP825gAmH18ASwpqD0vYvORsqY1JeLMWv1WSXtxcKBge9eMlrt8UeUiKPtnRDLe7zuoeaiI0BBpG6bPMb4748Gm2MMEjEMRdiEm5VkF5QaLxVYgs6sG6EnjckihkivneYHGmNCgBVP9h0idYcjBp08sH7kN7o8xZS6XyAI2A8sln4cm', 'sample_jOWhHNwQUt1uJx2kPyP1w12xx0VmItQqrpMFoAK5Q5hzAwk6IdTs6Zs4O0fk3TBmFAOgiAO9uWZqt4c', X'4FEFAA9A7DEFA08134185EE2B8A908', 'y,x', NULL);
INSERT INTO t3 (c1, c2, c3, c4, c5, c6, c7, c8, c9, c10, c11, c12, c13, c14, c15) VALUES (5671, 6432, 994, 2007, '2023-01-01 03:06:53', 9, 46, 38, 20, 'sample_IgunjWtOnhzMxUH9Ad6ztAz1RATtk0dLGWZI04tEFxDc3YGNltqWLpjA1Zdiy0PzXAPr446Tqj0z4WKHyW7vRqz4XwCvGBYI2jaMMRvhftO4q2uNb8GqE4pITSPpgZnqO6QNHAMfDUSy413xdlhdBXRHUiFNmfld6A6pRgpBbo69hf6MpqhA4uKL4fT7lunYOzXI7ftuq3I8izzucoUA1LLfeMezTjFSYGQ5YWSq4wYPS4xh5ip5FdYmEHV1U6S3EBtFEjzgWSVcU', 'sample_2xSG6kX0B2smVHvvQD77wD26NFKaoY3vFA1Ty5whGT50gMyzP69v8mQNea4TTSnfikdbSOjlgnF3mpiXkmNPVHfDG5TP6E8Z3spsOedSyucPJ7iS91t4SXWQh5nEl70ciocI1tqu', 'sample_V9eyQD3ic2DoRT53i76gSpkmcH7Ge0SLXYqppVH1yO6thE1RMpOZxm6R', X'E9AF89E69587', 'z', NULL);
INSERT INTO t3 (c1, c2, c3, c4, c5, c6, c7, c8, c9, c10, c11, c12, c13, c14, c15) VALUES (1609, 9828, 2120, 2002, '2023-01-01 16:32:23', 38, 39, 92, 58, 'sample_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', 'sample_BG5pG2qcXsHF4L2NnVrMX6VTic5BkzqnbWb56WsXYkJZnDQiX183nLVfMWUowf5wXKKCVpvdOb0cnmozbVE8rTNsCWOaNUs7IIUqI79ChL14Dh9UjofKJF0BYN8NnMd7VmeVUt98C8dvr20RY33brrBsRaUxUdg0Gs6JhAKl1PxZcRyTxSlSWn1SEiKU', 'sample_bVEDTl6xDaU5w7nREFRKU', X'CDBADAB6EFACA50AEF8896D6A2', 'y', NULL);
INSERT INTO t3 (c1, c2, c3, c4, c5, c6, c7, c8, c9, c10, c11, c12, c13, c14, c15) VALUES (7662, 3575, 8014, 2013, '2023-01-01 16:34:04', 58, 36, 81, 92, 'sample_ZYXx0jWNki2xSSWM80Pk0t5y1S69Ippf59cH4yspbVUBeBRTjRGftcS2zpHJCUxWdgskmomJa6yPpv8JKQYNoYlHP3UZYVMgT9Wgy76qfWesHSWT9t1UXhobg8nGLFf9F5mBLd7jMIscsEV4ulC4F3WOh1dei3cyJRzGWHRRxAr62djzEphLrqYVrm4s0l0P9YKY4IgYvgXfHRczZXNJWgLvc3O2TVVkqj3sliZvQ8YPuFCqYvqik59QBtXXfNUBrfHZepgUlURfsyLj3ppfhnv1JdZdAYG5X4Yl2yhrceimJD4RDONSwL2O7KYkQ3PipIqDPfQDlLeHbdbkIGavRlBxEfJC6fYEEqhwWbyl8nQOHWBASOIQML51vIoFkda2C7CQr0qspDzKAau3rl87W0N2lajDgAlpJsxyiwhW1blUoDrJm9hYhdDGUkt9zkQ6rIJJ9286dhqdOIrJJwVdHbavbRex4NDFV1', 'sample_hLPagUYlEWWjb9olaeLGiWFAWM4OIKbBpmev1YsHZWICVTtLi4Fs4Ss9LA2oPAavoQjI4BLZeoJoTh3TPWDeiNQOtTaznv7XsckzUH4ypZgAfRdXaq3gMZvMNHMdFcerfkJczqSQiilsuxVMseX8epVtHdzrthGWC7lVkqXlifeOWsR7Tdparrt44HEuLl46bBxKvjTCgrDMOAsQBo73KK6qpI6tMtGzhz0CpkB', 'sample_MDKFYRuzw0d6JJHddMPvXAVuHNE2X6CVBoxJ2BH4yw5nTQf0gQYGeMdKH900NmORF82WS5huG0OxkXIWeRlV7APNWkiwyyeUbw8ytpB26Uo9WWxuybXnGdXUjThbIZOgrNwWv2Ephk1cSZofIRIiZMpODR6CSYFFwTpF24AIpyqMUjrH2rFfPgiVtkuIXZw', X'E8A098', 'z,x,y', NULL);
INSERT INTO t3 (c1, c2, c3, c4, c5, c6, c7, c8, c9, c10, c11, c12, c13, c14, c15) VALUES (5327, 1986, 5873, 2017, '2023-01-01 01:51:13', 77, 36, 40, 23, 'sample_CEI6RZi4sS9VmrP0B6sNnhYKDluvxud85L33zADk9nGHjOj0pFuqalbyx5iNWLNLCAWigtTbCA98HB7Bvj7TotEj7NkjrFqEf6yGMLIxMLUngoKe5dwvWFmEYrwd5fNlws3eq8RS4nrWJGcs8Pm5QZd90vLekOYJz35skCWMvV9K9MghXU90CrpeavGjEzjeH0iWJi3vMtMo8pmrnXi5wwxyjqW3AexTmNrzMtLpowaE24po00igflU13WoUkYORDZGnigHRG2AUAu0PMnltmDZ0si8TFPNksWzdH5oEHvRf3b6tjmYjmIGpcYTHHjUujbabxntxs0mZF9czPHWcKzUFC3DGnZWNlMKLVugmpiirkauE0qHLbtwkgJa0HBk3bQdUZ3emsME7fQWQM3DIUZ8ywdbiBzMKPxEOAjZz4wicXiF4OtPP5IAFyEPEf4Go0idRCm6FCvZBIiLCvTbF4ZMPNeG2GsP2GczOydz7A1XgV2T2PbXty6sHyJffCBeZyRXaz1WKUZ9N8tWArnG2Vz4y7Sqxj3Qh8jDIJIPxggCNlGU1frgbgPWjatujZX3zIOQlshIwCsF6sRWUYlVXNHq6kvxKLOx40dLiHhdZ8blNLGx4lY3ID3iGzbzV4przbuAMBt1NS4MigKUTgBeX0lxUHZ4ywr5C3DitvrMOdlk7MMYsZFfMIOKTPM6BRSf5MeAfGKzoghdVwxnLkTZbv4nLwSECFF45fDXL2B4eb8NnJqw3AlgwEbdJ7FaedSNcf7NRFptgx9iGhsk7VHkHMV4zn3DDTcntHD2kHgNrspCZvkiDTbTrgk1nRXfOAGKkuXWElPfjRFRxl4VDd6jnhlFGMlRWNnLgdUPHjUQmGrZOoLUpyqWzekNLZlUuRpaUiNOsUsNplTQDLaI8PeDayNvR3kktR3eoeaxThnJvghKsge2XKpoaD939bjSBLKCLtt3aO2mqYuoD5CuMyopV5cV4ttQxpMjmzvDvTzSeRi5AHg6kgWXCdsOird0t9TXwKejkh0wPsENSHEioPaeWWIE22zDru4u3KvyN3stw1nRE7Zek0eu5eQ2bLktCswtt0RnMN4jaXetVJoLPAoPHpoXj0rUfEd9v9zrDrGjuQDViOKlZWHfWYAWVw8fks7ExZy4fLDG03qt3uGZiAmZJ98RggR8awQRG65rmZqa5gUA6i6R55TPKJXGggM9wjI6j3bsw3932lZkdc67YiCQxO5TXLV2ggd39BG6FKeBCt58VOilRVklLirSwkbtr9YubiywfucIM5ResDWICOnveHVFGvq2VtXZEpOYpPDf0mbGBjrudFfdUq0clVpFK03XOUgBF17MbPBapKfQXIGHrkFi1l0zwqtbdlKnbmr4QEDirivrQtuy5CdE13We3V2ANclbwRQQUqPFCQk0Ma1958z1reNoCX947i2fpEeVDG9BKl2Yo4sGt1EkRqPfvangZoTzm3OOjURald3nFbKO81uHzBBCXyk5SxqV7oX8FPWFmS5dN3qe3thvXSCrtrkOJk2OvGZXmvOKhKVlHyJBVdYmSdnsVpn79QiGLWjwgiZhRC3ypOcTp84hB6tIaYe7a1QRcNMtNNWFzqqKYlptAt1MOPGTCD99zkJQDttJBQXAZd1gWz2rrshYMojLB6Q5hEmI0YYbbOd7JxM7LjSjQpQZTVLl5bCxWrDj36pkWQYVmxDSbou14qNlXkpJLeStxrbxUycsuogMzKgR04ywDroYNDAKS6n54JIn8JrEEHYq9EXTWt4aiwJ2wZAnug7QNYRG6oCrICsYmWOVNIvpaWMElCDJ8tHwTCZFqTlVIY1Fxdinor0Scq9HbGmaR57lYoshHrzNijBTf', 'sample_XxGNl805IYKpWIxvgsQx6edzTtGu9WetHh1rEQwlBFlyLNpzuC3hl6YtCYCVLUOK1PgrS4hWMYregQ8rmuLnAi3R19Hu8J4xmyzQxq3xRAuG05RRLH9SVxIzPiPzUUj1M0sNVlbWeo7Bsj1fGdikvihk03k2oZNBl6s0pTE1IsYJAN4NF0YAuz5sXbmlFF3z5P9N4aCkYNyp2bLXwLr2vtn1zaMwdZRjLiMv6jUjPCbWWizAlwJbjEvR', 'sample_xtYtZX7P6NTSiMDgPfofmCwIseZ7yFsndYvbmoRkeD06qkUr5uBpq1APXs', X'CBB3', 'y,z', NULL);
INSERT INTO t3 (c1, c2, c3, c4, c5, c6, c7, c8, c9, c10, c11, c12, c13, c14, c15) VALUES (6321, 2932, 2120, 2004, '2023-01-01 07:36:33', 12, 38, 82, 70, 'sample_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', 'sample_BP', 'sample_ThYy03eQiJaSHY7KzuyTncEDzJ5dE9FYJQEdmPyJPa9LwsyfdQNf1AWAETPXC5SCTXNHDo8YsWwwqQo1mVDfxSY01ea1BlU7wJJRX0kbiNjyk9E4puutfqeC4wzewwTCkJXchV9eL37LQux62y6Suq2rue0QoR7sfX2FGEacx6MD13jAVUE3AB0LiwGT', X'D58C4BD2892AEFA9864AE785A70EC1B47FD99F58DA9FE9A281DAA42043504B6B', 'x,z,y', NULL);
INSERT INTO t3 (c1, c2, c3, c4, c5, c6, c7, c8, c9, c10, c11, c12, c13, c14, c15) VALUES (2035, 4556, 2340, 2005, '2023-01-01 07:09:27', 0, 65, 15, 25, 'sample_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', 'sample_Oasx8mRwcgxWOtWI2XmI7hvvvZy75on6KQbqEOCpmDbvwxeuTZYlgYSBHiayIA6J5ORww8Ow4glWF2qkn54bQO4zGe4iffsK0iM5xdEN', 'sample_XRJcMMznYlkdgcuS5QF6qGos1MT5etBPlbioyiT289RfjzZqJTUkQw3jz1kx2uYaykOKjypRemP4O3sEW49jr6KhfMiA9KS4gvMv3j6xBK', X'E381B4DBB769C69D22E4998D0BCBBED1A1E99EA30ADB9DDEBBD799', 'y,z', NULL);
INSERT INTO t3 (c1, c2, c3, c4, c5, c6, c7, c8, c9, c10, c11, c12, c13, c14, c15) VALUES (4150, 3423, 994, 2003, '2023-01-01 22:43:46', 19, 46, 49, 46, 'sample_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', 'sample_1VdfXOZwAA4G6o3RYgz850VXncj4EUsRl8nuHMOZTmfMmEk3TT78y8OOss7HnLaijg004Owa13ynjc65yeM1HgHWe0qRMiZleNVyiP7iVQk6sy5VTe4l7Mazdzu2K3tEwksyWPz1wJnRQkrAZxgC69sqdp77jU4sRP2qNgYXMibMW6zhnJ8Sn33i', 'sample_NKrUyPT9yMvvuX8PwWn6oECfFCv0W1H5QldTeI08zXXI12aksPGk0QSdopZ46GnXhL1QQBO0bHIDmwxf1GKSLQ99yHMnrABPzTtD3wVKKbBfTv8mGwbZCCBKDEBBN564NdRWzOmMFTlw4AGihpHTJ8Xhk3QasPu1wk', X'CD9B46E8B5894D5E7D', 'z,x', NULL);
INSERT INTO t3 (c1, c2, c3, c4, c5, c6, c7, c8, c9, c10, c11, c12, c13, c14, c15) VALUES (4922, 954, 4869, 2021, '2023-01-01 06:36:18', 19, 50, 55, 65, 'sample_NTrYxKtQPl4FLrt24vkLQoT1gVcntayj1ARA9aRcMcKJxzZ82CCc7KWUdvhCnRlauUts8Klnk5S79chFkzYWOukbINHH8INiGGDXMCKWdARClW7JeGw4v2RHPiv1ujOHwwIHu2TvzZGGEvhnc138wpYgly2rDNgzNl8NfADtOSn8aA5BrUHGnievhwBCU1t7ckh2yvJmBIhG7TEE2xbwedQ', 'sample_9aBiOKQWlD6V8bnMlAnngXZ1YieyzuAPe18BnchnfXv6jiQr7DaO7p8iNRIy3HRcpus3SXH95WlUixQOUStr548OLHbSdgpkqOTlSazJIaPLHIMFBW9KE3D', 'sample_UmiYLgxZvp53mPtZvonfQqC6O5HoEmaq7nUw0', X'ED8D8C70E98E9C434E5D0D4EE589A67BC392E182A6CE82C999D9BB54', 'y,x,z', NULL);
INSERT INTO t3 (c1, c2, c3, c4, c5, c6, c7, c8, c9, c10, c11, c12, c13, c14, c15) VALUES (7547, 8711, 5257, 2017, '2023-01-01 01:17:28', 87, 47, 5, 26, 'sample_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', 'sample_8Qhk551ndz', 'sample_cfyuAkinznRvU0c0aPjqz1pAOg5KwPVMLVOJn5ChxShtY1lN7JV1HXS2gMrMhWMbTzlfBKZsuIU3OjwzsU9sEFiNQIDfVn5bOvEr8hOLGOn3mARFY4KS9IeUZ333QNsBlWR1SwkvMvwJrA8XrTkFeCvJIu5azvthOaDBMjiiFa7Da91VBlVreroqCDw1gUE1B', X'53E59A96E5BD88EF96A4122503356D44EDAFA5037A01', 'y,x,z', NULL);
INSERT INTO t3 (c1, c2, c3, c4, c5, c6, c7, c8, c9, c10, c11, c12, c13, c14, c15) VALUES (508, 3423, 3833, 2023, '2023-01-01 15:58:27', 65, 7, 72, 41, 'sample_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', 'sample_zY7y3rZ6f6WeetxJCh1OVoZJT7wXaQndkDnPevbbVjRpzImP8cBImei', 'sample_qRQbjno2fuVAPuEzsA1w0q8ws5VWmDcJtp5Nr', X'C086EE9BAA', 'y,z,x', NULL);
INSERT INTO t3 (c1, c2, c3, c4, c5, c6, c7, c8, c9, c10, c11, c12, c13, c14, c15) VALUES (286, 3584, 2120, 2012, '2023-01-01 12:56:07', 6, 14, 76, 45, 'sample_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', 'sample_bjeIiqUKL3iQP8LNL6WXNthn9CdBIPZ8twK828', 'sample_SgtMwOIlqGZqrrsU0tEV7Ciy6jFnIA91c9eq1Jes3HMBCnNy2m', X'E2AB84DB9DDCA1E49C92EABDA4443BED888C7D4B6D5C7C41E2B986EBAF84443943C285D2A9E6A7AED98FDA8D28', 'y', NULL);

SELECT DISTINCT xnt48.c3 AS col_1, xnt48.c14 AS col_2, xnt48.c7 AS col_3, xnt48.c8 AS col_4 FROM t3 AS xnt48 WHERE (COS(xnt48.c3) < 49) AND xnt48.c3 = 2120;
SELECT DISTINCT emc88.c4 AS col_1, emc88.c3 AS col_2, emc88.c1 AS col_3, emc88.c1 AS col_4 FROM t1 AS emc88 WHERE '1' = '1' UNION ALL SELECT DISTINCT xnt48.c3 AS col_1, xnt48.c14 AS col_2, xnt48.c7 AS col_3, xnt48.c8 AS col_4 FROM t3 AS xnt48 WHERE (COS(xnt48.c3) < 49) AND xnt48.c3 = 2120;
```

### 2. What did you expect to see? (Required)

the col_3's value changed after adding a UNION ALL clause,the second query's result is correct.

```
mysql> SELECT DISTINCT emc88.c4 AS col_1, emc88.c3 AS col_2, emc88.c1 AS col_3, emc88.c1 AS col_4 FROM t1 AS emc88 WHERE '1' = '1' UNION ALL SELECT DISTINCT xnt48.c3 AS col_1, xnt48.c14 AS col_2, xnt48.c7 AS col_3, xnt48.c8 AS col_4 FROM t3 AS xnt48 WHERE (COS(xnt48.c3) < 49) AND xnt48.c3 = 2120;
+-------+-----------+-------+-------+
| col_1 | col_2 | col_3 | col_4 |
+-------+-----------+-------+-------+
| 90 | sample_sQ | 954 | 954 |
| 36 | sample_v | 3584 | 3584 |
| 2120 | y | 39 | 92 |
| 2120 | x,y,z | 82 | 82 |
| 2120 | y | 14 | 76 |
| 2120 | x,y | 4 | 4 |
+-------+-----------+-------+-------+
6 rows in set (0.00 sec)

mysql> SELECT DISTINCT xnt48.c3 AS col_1, xnt48.c14 AS col_2, xnt48.c7 AS col_3, xnt48.c8 AS col_4 FROM t3 AS xnt48 WHERE (COS(xnt48.c3) < 49) AND xnt48.c3 = 2120;
+-------+-------+-------+-------+
| col_1 | col_2 | col_3 | col_4 |
+-------+-------+-------+-------+
| 2120 | x,y,z | 38 | 82 |
| 2120 | y | 14 | 76 |
| 2120 | y | 39 | 92 |
| 2120 | x,y | 23 | 4 |
+-------+-------+-------+-------+
4 rows in set (0.00 sec)
```

### 3. What did you see instead (Required)

```
mysql> SELECT DISTINCT emc88.c4 AS col_1, emc88.c3 AS col_2, emc88.c1 AS col_3, emc88.c1 AS col_4 FROM t1 AS emc88 WHERE '1' = '1' UNION ALL SELECT DISTINCT xnt48.c3 AS col_1, xnt48.c14 AS col_2, xnt48.c7 AS col_3, xnt48.c8 AS col_4 FROM t3 AS xnt48 WHERE (COS(xnt48.c3) < 49) AND xnt48.c3 = 2120;
+-------+-----------+-------+-------+
| col_1 | col_2 | col_3 | col_4 |
+-------+-----------+-------+-------+
| 90 | sample_sQ | 954 | 954 |
| 36 | sample_v | 3584 | 3584 |
| 2120 | y | 39 | 92 |
| 2120 | x,y,z | 82 | 82 |
| 2120 | y | 14 | 76 |
| 2120 | x,y | 4 | 4 |
+-------+-----------+-------+-------+
6 rows in set (0.00 sec)

mysql> SELECT DISTINCT xnt48.c3 AS col_1, xnt48.c14 AS col_2, xnt48.c7 AS col_3, xnt48.c8 AS col_4 FROM t3 AS xnt48 WHERE (COS(xnt48.c3) < 49) AND xnt48.c3 = 2120;
+-------+-------+-------+-------+
| col_1 | col_2 | col_3 | col_4 |
+-------+-------+-------+-------+
| 2120 | x,y,z | 38 | 82 |
| 2120 | y | 14 | 76 |
| 2120 | y | 39 | 92 |
| 2120 | x,y | 23 | 4 |
+-------+-------+-------+-------+
4 rows in set (0.00 sec)
```
### 4. What is your TiDB version? (Required)

```
mysql> select tidb_version();
+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| tidb_version() |
+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Release Version: v7.5.1
Edition: Community
Git Commit Hash: 7d16cc79e81bbf573124df3fd9351c26963f3e70
Git Branch: heads/refs/tags/v7.5.1
UTC Build Time: 2024-02-27 14:28:32
GoVersion: go1.21.6
Race Enabled: false
Check Table Before Drop: false
Store: unistore |
+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)
```

Start by running the SQL reproduction against TiDB and isolate the UNION ALL query that changes a column value. Compare results with and without UNION ALL, then add a focused regression test in the relevant SQL execution area once the affected behavior is identified; done means column values remain unchanged and the reproduction passes.

Written by the indexing model from the issue text.