Here's what that reports using Basilisk/Windows. Default (no TZ set):
As expected (although I'm sure when I did this a bit earlier the Beat was @40).
Setting TZ=UTC:
So DateTimeFormat still has the proper value, as does Timezone (and Beat, I guess). That suggests to properly spoof it you'd have to modify system time itself (in the OS or hooking the calls or direct browser support).
CODE:
Time on ServerMon, 03 Mar 2025 23:57:42 GMTTime on Local MachineTue Mar 04 2025 10:20:57 GMT+1000 (E. Australia Standard Time)Time from Intl.DateTimeFormat #1Tuesday, March 4, 2025 at 10:20:57 AM GMT+10Time from Intl.DateTimeFormat #2Tuesday, 4 March 2025, 10:20:57 am Australian Eastern Standard TimeInternet Beataround @56TimezoneAustralia/BrisbaneTimezone Offset-600 minutesSetting TZ=UTC:
CODE:
Time on ServerMon, 03 Mar 2025 23:57:42 GMTTime on Local MachineTue Mar 04 2025 00:19:34 GMT+0000 (UTC)Time from Intl.DateTimeFormat #1Tuesday, March 4, 2025 at 10:19:34 AM GMT+10Time from Intl.DateTimeFormat #2Tuesday, 4 March 2025, 10:19:34 am Australian Eastern Standard TimeInternet Beataround @55TimezoneAustralia/BrisbaneTimezone Offset0 minutes