format('x') result is different from moment

**Describe the bug**
see code below:

```js
const dayjs = require("dayjs");
const utc = require("dayjs/plugin/utc");
const timezone = require("dayjs/plugin/timezone");
const advancedFormat = require("dayjs/plugin/advancedFormat");

dayjs.extend(utc);
dayjs.extend(timezone);
dayjs.extend(advancedFormat);

const date = dayjs(1704437980110).tz("Asia/Tokyo");
console.log(date.format("x"));
console.log(date.utc().format("x"));

// result:
// 1704441580110 // <== wrong
// 1704437980110
```

```js
const moment = require("moment");
const momentTz = require("moment-timezone");

const date = moment(1704437980110).tz("Asia/Tokyo");
console.log(date.format("x"));
console.log(date.utc().format("x"));

// result:
// 1704437980110
// 1704437980110
```

**Expected behavior**
Get same result with dayjs.

**Information**
- Day.js Version [e.g. v1.11.10]
- OS: [macOS]
- Browser [ 120.0.6099.1292]
- Time zone: ['Asia/Shanghai']

**Others**
`$d` is changed after `tz('xxx')`, so `$d.getTime()` caused this.

Start by reproducing the issue with the provided Day.js utc, timezone, and advancedFormat setup, focusing on format('x') after tz('Asia/Tokyo') and after utc(). Trace the timezone and timestamp-formatting entry points implicated by the reproduction. Done means the local-time and UTC format('x') results match the original timestamp, as in Moment.

Written by the indexing model from the issue text.