Midnight suns is a weird one. It's like Titanfall 2, gets crazy critical reception, but it's just not popular for one reason or another.
Did it? RPS was probably the only source that I follow who really loved it. Others were mixed.
I thought it was generally agreed that social sim part is between poor-meh, and combat is fine, if a bit shallow and lacking in variety. At least that was what most of reviewers I follow thought - and when I tried the game during the free weekend it was more or less my impression as well, thought thankfully, due to not particually caring about Marvel I wasn't offended by the writing. I will be picking it up once it drops to a price I will be more satisfied with.
I do think it is an awkward title. I am not sure how appealing is to mainstream Marvel fans, while it will probably be a bit too shallow for strategy fans. From what I played it seemed like it would be better suited as a mobile game - a nice think to pick up and click for a bit, but not something you want to sit and play for a longer period of time. If I had a Steamdeck, I would play it there.