Karlender has done what Calendar has yet to do: have adaptive interface scaling! Gone are the days of having to mess around with app patches, Karlender does all you could want from a calendar app. Set and manage events, tell them to repeat and sync all your upcoming meetings with any Cal-DAV service. Now you can forget your friend's birthdays from the comfort of your mobile Linux devices!
You can get the app on Flathub here: https://flathub.org/apps/details/codes.loers.Karlender