We’ve actually not seen a lot of trouble with the final release (read: “non-beta”) version of Catalina in regards to WoW.
There have been of course a few issues cropping up specifically with older Macs that were below the official minimum requirements for the game, but sadly that can’t really be helped - a new OS generally also means it requires more system resources for itself than its predecessor did, meaning there is less left for a game to exist on. If the game requirements are however properly met there should not be any reason to not upgrade the OS. 