The Google Calendar integration randomly breaks with no warning before or after, so the only way to know that it's broken is if you see that an event was created in HighLevel and not in your Google Calendar.

HighLevel support's recommendation is to go into Settings>My Profile>Calendar Settings>Calendar Configuration>Linked Calendar, and change the setting to "Do not add new events to any calendar," save your settings, refresh, then change the setting back to the calendar you had selected before.

If this is really the only way to prevent events from being created without a team member being invited, the HighLevel system should automatically refresh these settings every 2 weeks or so, rather than expecting every user to do this manually.