The function "format" would be broken after "utcOffset" being invoked twice and more

**Describe the bug**
As title. The `format` function would be broken after `utcOffset` being invoked twice and more.
For example:
```
dayjs().format('YYYY-MM-DDTHH:mm:ssZZ')
// 2024-02-17T15:14:51+0800 // Now

dayjs().utcOffset(300).format('YYYY-MM-DDTHH:mm:ssZZ')
// 2024-02-17T12:14:51+0500 // Correct

dayjs().utcOffset(300).utcOffset(300).format('YYYY-MM-DDTHH:mm:ssZZ')
// 2024-02-17T15:14:51+0500 // Wrong

dayjs().utcOffset(300).utcOffset(400).format('YYYY-MM-DDTHH:mm:ssZZ')
// 2024-02-17T16:54:51+0640 // Wrong

dayjs().utcOffset(300).utcOffset(240).utcOffset(120).format('YYYY-MM-DDTHH:mm:ssZZ')
// 2024-02-17T13:14:51+0200 // Wrong
```
But the results of `valueOf` are **all the same**.

**Expected behavior**
The result should be calculated by the last `utcOffset`.

**Information**
- Day.js Version: v1.11.10
- OS: Windows 10
- Browser: Chrome 121.0.6167.185
- Time zone: GMT+8

Reproduce the chained utcOffset examples and compare format with valueOf; start at the format and utcOffset entry points named in the report. Done means format uses the last utcOffset while valueOf remains unchanged, with regression coverage for the shown chains.

Written by the indexing model from the issue text.