Instead of getting Abbreviated named offset I'm getting offset

**Describe the bug**
while using trying to get abbreviated named offset. I'm getting offset value in return.

**Expected behavior**
On using the below code, it should return EST or IST but im getting GMT-4:00 or GMT+5:30
"dayjs.tz(input, zone).format("z")"
**Information**
- Day.js Version [1.11.12]
- OS: [Linux]
- Browser [all]
- Time zone: [GMT+05:30 IST (Indian Standard Time)]

Start by reproducing the reported call, dayjs.tz(input, zone).format("z"), with the supplied Day.js version and time zones. Trace the timezone formatting entry point and compare its output with the expected EST or IST abbreviations; done means the call returns the named abbreviation instead of GMT offsets, with coverage for the reported zones.

Written by the indexing model from the issue text.