Description

When the user's timezone is significantly different than the timezone that WordPress is configured with, the DateTimePicker component displays incorrectly. The first day of the month that is being displayed is the last day of the previous month. This causes some days within the month to disappear.

Similar issue to #29306 however this targets the month's display.

Step-by-step reproduction instructions

1. Change your local machine's timezone to somewhere in England.
2. Set WordPress's timezone setting to Los Angeles.
3. Edit or Add a new post.
4. Open the DateTimePicker component by trying to schedule a post.

Screenshots, screen recording, code snippet

Environment info

• WordPress Version 6.1.1

Please confirm that you have searched existing issues in the repo.

Yes

Please confirm that you have tested with all plugins deactivated except Gutenberg.

Yes