Description

In the post editor, clicking the "Now" link under Publish causes the last date of the month to disappear from the date picker. However, clicking on the second-to-the-last visible date will automatically select the correct last date.

Step-by-step reproduction instructions

1. Open the post editor on any WordPress.com site (Simple or Atomic).
2. Click on the "Publish" settings.
3. Click the "Now" link to reset the publish date.
4. Open the date picker — the last day of the current month is missing (e.g., Dec 31).
5. Click on the last visible date (e.g., Dec 30) — it auto-selects the missing Dec 31.

Screenshots, screen recording, code snippet

Environment info

• Wordpress 6.9. Gutenberg 22.3
• Twenty Twenty Five
• No plugins (other than GB) active

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

Please confirm which theme type you used for testing.

• Block
• Classic
• Hybrid (e.g. classic with theme.json)
• Not sure