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What this is @trishmac4 is a perfect example of how poor King is at quality control. Dexter was (is?) a character that was the face of many events (Dexter's Delights, Space Race), but Dexter was removed in 2021. The fact that King still references Dexter after they removed the associated Events really shows how little King care about their customers experience.
I haven't seen the 'Dexter' warning for quite some time myself, but I am sure I remember that it appears when you select an Event in your Events screen. It usually means that there is a problem with the Event you are trying to play, or the Event isn't live at the moment.
I don't remember the 'Dexter' message preventing me from playing a level though. Can you not play your game at all?
There is an issue with Facebook at the moment @trishmac4 which you can read about in the Article linked below. This is what is probably causing your issues. All you can do is wait and hope that Facebook/King sort the issue out