Wrong result when manipulating timezone date

**Describe the bug**
When I use dates in a timezone and add a duration the result time looks bad

```
const dayjs = require('dayjs');
const timezone = require('dayjs/plugin/timezone');
const utc = require('dayjs/plugin/utc');

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

// Accra timezone is in UTC + 0 so UTC time and Accra time should be same
const startDate = dayjs.utc('2022-04-05 12:00:00').tz('Africa/Accra')
console.log(startDate.format('YYYY-MM-DD HH:mm:ss')) // Result => '2022-04-05 12:00:00'
const endDate = startDate.add(1, 'h')
console.log(endDate.format('YYYY-MM-DD HH:mm:ss')) // Result => '2022-04-05 11:00:00'
```

**Expected behavior**
As I add an hour I expect to get '2022-04-05 13:00:00' and not '2022-04-05 11:00:00'

It seems to be related to the browser timezone. I am personally in Central European Summer Time (GMT+2).
But if I change the timezone of Chrome with devTools for 'Africa/Accra'. The problem doesn't seem to happen again
Obviously when I look at the open issues I am not the only one to have problems with the timezone, is there anything planned to fix this? Thank you in advance :)

**Information**
- Day.js Version 1.10.7
- OS: Ubuntu 21.10
- Browser chrome 99
- Time zone: Central European Summer Time (GMT+2)

Start by reproducing the provided Day.js UTC and timezone plugin example in Chrome with different browser time zones, then compare the displayed result with the expected 13:00:00. Done means adding one hour preserves the expected Accra wall-clock time regardless of the browser timezone and the regression is covered by a test.

Written by the indexing model from the issue text.