Makes interesting reading. I don't claim to know what's true or not. I haven't and won't be installing Catalina and so far I've deleted the iOS 13 update every time it's shown up on my phone.
https://support.busymac.com/blog
https://www.2doapp.com/kb/article/all-lists-and-tasks-deleted-in-2do-after-upgrading-to-macos-10-15-reminders-or-ios-13-reminders.html
I did hack up an applescript that would pull Reminders out and insert them into Todoist (my alternative to GoodTask). It is here: https://github.com/posguy99/AppleScript/tree/master/Todoist