I think Onana is just a scapegoat of Amorim's failure. I do understand that he has made a lot of high profile errors and as a GK, his errors are more expensive but I believe he deserved as much benefit of doubt as everyone else.
United finished 15th, Onana was shit and got dropped but nobody is coming after Bruno, De Ligt and the other people that were shite and led to the 15th place.

Goalkeepers have a very sad role. No one remembers them when they do their job and they get scapegoated whenever they make a mistake.

You can't outscore goalkeeping errors but I still maintain that even with those two errors, a premier league team should be outscoring Grimsby. It had whether it is Manchester United or Burnley.