Google’s online calendar has removed default references for a handful ... it added prior to last year's change — and ...

Default entries you may have seen on Google Calendar in previous years, like Black History Month or Indigenous Peoples Day, are no longer automatically listed. Google clarified that it made the change ...

Although it sounds weird, the date and time settings could be the reason for your Calendar-related issues. If you don’t set them correctly, Google’s servers might have trouble syncing with them.