Being run by the project developers left after the primary dev’s departure and (if you’ll excuse the drama) betrayal by selling to what amounts to an advertising company. Personally I’ve started supporting this project on github, as losing these tools would be a massive blow to the open source Android ecosystem.
Can I transfer my calendar stuff from Simple Calendar to this one?
I believe Android calendars are stored and managed outside of the apps themselves so whatever you have will probably just transfer over. If not, you can get an ics export.