Date fields in Drupal 9 lack timezones and this is needed to allow events around the world to show local time accurately
- drupal 9 datetime field lacks timezone
I found the core issues about this problem.
[PP-1] Add ability to select a timezone for datetime field [#2632040] | Drupal.org
Here’s the issue set aside for patches that can be applied with composer to fix the problem!
https://www.drupal.org/project/drupal/issues/3185750
Disappointed the fix isn’t (or maybe can’t be) in https://www.drupal.org/project/datetime_extras