Agreed, I felt the “monster” or evil behind the door was better left a mystery for a later movie or something else. The heart of the movie to me was the relationship between the characters.
The father-son-daughter struggle for an ending would have been better to me. I think Marvel can take risks but they need to take risks like not having a third act battle all the bloody time!
Aren’t inverted commas also a phrase for that? Or is that the joke.