Two Catalina bugs that keep recurring for me:
1: Every now and again, it decides that I'm no longer allowed to write files to the desktop. I have to restart to be allowed again.
2: My exchange account in Mail sometimes pops up an error claiming that the mail I'm writing has an "Invalid Base64 string for MIME type" and it can't move the message to the mailbox. Then moves it anyway.
I wouldn't mind but it seems that as well as being more frequent, the error messages are getting increasingly cryptic in their phrasing.