Any way to stop creating 'TV' folder in ~/Movies on macOS Catalina
Short answer? Yes and no.

You can tell TV.app to change where it will store its library by opening the app, going into preferences and then under Advanced choosing a new location. This may not move the current folder, but will create a new one in a location that you prefer, so you can freely get rid of the one under ~/Movies/TV.

However, if you don't have a TV.app library, and never open the app, then once you delete the folder it should stay gone. Of course if you do open the app, it will be recreated, this may also occur if you enable home-sharing for that account, even if you're only sharing music.