I know there’s already a way to remove UB options and printings from searches, but bulk editing, importing and generally just forgetting to add the string to searches all still include the UB versions of cards, which becomes tedious to switch printings to non UB ones each time. Some button or toggle setting that automatically excludes UB versions of non-UB cards would be greatly appreciated!
I’m not sure if this is a perfect solution, or if it’s the solution you mentioned implicitly at the start, but under User Settings -> User Preferences, there is a Default Scryfall Query, I think if you add “not:universesbeyond” to that (excluding quote marks), it may give the behavior you want, at least partially.