Previously, I've used the CalDAV api to add my personal google calendar to thunderbird. Pretty straight forward. Set the calendar location to
https://apidata.googleusercontent.com/caldav/v2/calid/events
replace calid with the appropriate calendar ID (your gmail address in most cases), and then an OAuth window pops up asking to log into your google account. Done.
For the past 2 days, I've been trying to add my calendar to thunderbird 91.11, but it always just hangs on "please wait while your calendars are being discovered", and I never make it to the OAuth step.
Can anyone verify that this process indeed still works on thunderbird? I'm not sure what I could possibly be doing wrong here.