Dates entered with the datetime picker using a time zone of "IST" are not displaying properly in posts. They look ok in the editor preview, but they break in the rendered page, throwing a red banner for site admins and showing the time as though it were UTC instead. Things all work ok if I use the IANA Asia/Kolkata tz.
Here’s the reproducer:
[date=2024-01-18 time=03:00:00 timezone="IST"] → 2024-01-17T21:30:00Z
[date=2024-01-18 time=03:00:00 timezone="Asia/Kolkata"] → 2024-01-17T21:30:00Z
Displays as:
