Google calender can't be connected

Hello, since recently I am no longer able to use my Google Calendars in Thunderbird. Environment: - Thunderbird 153.4.0esr, 64-bit - Windows11 - Google Calendar / CalDAV - No “Provider for Google Calendar” add-on installed Problem: My Google calendars previously worked normally in Thunderbird. Recently Thunderbird started showing that the calendar was temporarily unavailable, and attempts to modify events resulted in: MODIFICATION_FAILED I therefore removed all Google calendars from Thunderbird and tried to add them again. When adding the calendar using: https://calendar.google.com Thunderbird opens the Google OAuth login. I can log in successfully with the correct Google account and complete the authentication process. However, afterwards Thunderbird reports: “The entered credentials were rejected. Please check the settings above.” I have already tried the following several times: - removed all stored Google / OAuth credentials from Thunderbird - restarted Thunderbird - verified that cookies are enabled - verified that no VPN is active - tested the Google Calendar successfully in the browser - tried the direct CalDAV endpoint at apidata.googleusercontent.com - confirmed that the “Provider for Google Calendar” extension is not installed The Google account and Calendar itself work normally in the browser. The issue therefore appears to be related to Thunderbird’s Google Calendar OAuth / CalDAV authentication. Could you please confirm whether this is a known issue in Thunderbird 153.4.0esr and whether there is a workaround or fix planned? Thank you.