There was definitely alot cut out it seems.
For instance,
There was supposed to be a sentinel terror dog that walked on two legs that was cut I think during final battle.
There was also a film scene where a waitress gets covered in slime that did not make it.
Finn Wolfhard even mentioned in an interview something about an abandoned plot line.
As a GB fan, I loved it and still recognized there were a few things I thought could have been done a little better. Also felt like the movie needed another 20 minutes during the leadup to the final act.
I saw it twice. Enjoyed it more second time. My family loved it.