Or maybe team evil decides they’re random doors, opening to a different inter-dimensional dungeon each time you open them.
Or maybe team evil decides the dungeons repopulate much more quickly than they realized.
Or maybe team evil decides that the unreliable dope with the paint can who paints doors has painted the doors in an unreliable and dopey way.
Or maybe team evil will decide some other bugbear has been painting doors too, because they don’t want their favorite hunting ground messed with.
Or maybe team evil dies, and for the rest of the book is OotS has to figure out how to save the world without them.
What I’m saying is there are hundreds of potential “what next” scenarios, and choosing between either “team evil decides OotS did it” or “team evil decides MitD betrayed them” as the only options is a false dichotomy.