Hello SaeedFazlollahzadeh,
Welcome to Microsoft Community.
I tested the Tehran time question that you responded to here.
I set the region to Iran and change the time zone to Tehran:
Then I turned off DST:
I note that this option is still available, but it doesn't seem to be true because Iran no longer has DST enabled.
This issue should be fixed by Microsoft push update, for faster implementation please visit the link below and comment here so that developers can take notice and push an update to fix the bug as soon as possible:
Daylight Saving Time & Time Zone - Microsoft Community Hub
Mexico 2023 time zone updates now available - Microsoft Community Hub
The current update for Mexico's time zone is the latest
Best regards,
Mitchell - | Microsoft community support expert from MSFT