The Modded Realm should have a pop-up notification whenever you open the game, warning you that you are in the modded realm and explaining that any progress like maps completed or loot and experience earned will be lost when closing the game. End the message with ‘Happy modded rat hunting!’ or something and an optional box to tick that says ‘Don’t show me this again.’
I suggest this because there’s been quite a few threads asking for help where the issue was that they either didn’t know that modded realm did not have progression, or flat out didn’t know they were in the modded realm.