Thank you for the clarification.
If you work with hours, I think, it would be better to add the hour scale and the
hour duration unit:
That snippet will be loaded with the same dates regardless of the timezone settings.
I understand that users might add a task and adjust it to their time zone, while other users will think it is also their timezone.
server_utc option, the task dates will depend on the timezone:
If you highlight non-working hours, users might get the idea that although the task starts at 02:00, it actually starts at 08:00 at their time.
Another possible way would be to hide non-working hours: