Gnome Calendar is unresponsive after starting, then crashes
I configured three Google calendars using the Online Accounts tool in my system. When I open Gnome Calendar, it takes about 20 seconds to show the appointments in the first calendar, and another few seconds to show (load?) the appointments of the other calendars. Sometimes I get a Gnome window saying that Gnome Calendar does not respond with the question if I want to wait or kill Gnome Calendar.
If after waiting a few more seconds (or minutes!) I click on the left/right arrows to show the previous/next week/month/whatever, Gnome Calendar crashes (because it has not finished loading the appointments it would need to show?).
This happens on Ubuntu 19.10 with Gnome Calendar 3.34.2. The issues happen on different machines, so it's not related to a specific machine setup.