Calendar App on MacOS Won't Sync After 5PM I have a rather odd problem with my mac... None of my 4 Google calendars (2 gsuite, 2 normal) sync properly after around 5PM. The Calendar UI only shows The server responded with an error.
I've tried:

Clearing the calendar app cache following this procedure
Removing and re-adding these accounts entirely
Entirely removing ~/Library/Caches
NVRAM and SMC reset
Upgrading the entire system from Catalina to Mojave

The only clue I have is this line from logs is:
CoreDAVPropFindTask failed: Error Domain=CoreDAVHTTPStatusErrorDomain Code=403 &quot;(null)&quot;

But still no love. Does anyone have any ideas? This is one of the more bizarre computer problems I've ever had.
Seems to be a fault on google’s end affecting macos / google calendar integration.
The relevant google support thread is here