Incorrect query result

## Bug Report

Please answer these questions before submitting your issue. Thanks!

### 1. Minimal reproduce step (Required)
`CREATE TABLE t0(c0 double unsigned);
INSERT INTO t0 VALUES (0),(0.8077146669816686);
select count(*) from t0 where REPLACE("abc", CAST(t0.c0 AS DATETIME), true) is not null;
`

### 2. What did you expect to see? (Required)
The SELECT statement should return the value 1.
### 3. What did you see instead (Required)
The SELECT statement returns the value 2.
### 4. What is your TiDB version? (Required)
Release Version: v8.5.4
Edition: Community
Git Commit Hash: e4e814fdc0afe9c3a6e5e96f129d83df802ab820
Git Branch: HEAD
UTC Build Time: 2025-11-26 15:59:14
GoVersion: go1.23.6
Race Enabled: false
Check Table Before Drop: false
Store: tikv