>>238
https://www.thunderbird.net/en-US/thunderbird/102.5.0/releasenotes/
> After upgrading to Thunderbird 102.5.0, a one-time full resync of cached Google Calendars (using CalDAV) will trigger.

102.5.0のリリースノートだけど解決はしてるっぽい
全部の再同期が一度必要みたいだけど