Everything they do to Steve is even more anoying if you are a Steve fan, a Sam fan and A PEGGY FAN. Everything they did with Peggy outside Steve (aka both the What If...?s she's in and Agent Peggy Carter & other small bits in canon) made her grow FAR OUTSIDE OF BEING STEVE'S LOVE INTEREST.
I mean, she still loved him, but she was past it, living her own life, and now...now she's a mom (I'm going to especify, because I got some feedback on this, and I get it wasn't well explained: there is not problem with being a mom, BUT PEGGY HAD BEEN SHOWN TO HAVE HAD AN ENTIRE HAPPY LIFE WHERE SHE HAD NEVER WANTED TO BE ONE -I was given the note that she was actually shown with kids in the photos or her past, sorry, still, I will leave my rant because it felt so viscerally like this in the moment and it still feels as the writers saying: look! happy couple! they obviously have a biological child!). And she's not even the slightest concern about the fact that Steve sacrificed an entire universe where he was needed to play house. WHAT THE ACTUAL FUCK?!
And, taking into account the fact that she was supposed to have kids (which I had forgotten), Steve knew and still...nevermind, I still deciding what is worse: giving kids for a happy ending to someone who had been shown to not needing them to live a fullfilled life, or taking away those she willing have for some character assassination of one of the previously greatest characters of your entire universe (and, in either case, the last part of my rant is still valid).
So yes, in summary: Steve Rogers character assassination and Sam Wilson's absolute disrespectful treatment is also flavoured with some downgrading of one of your most well known female characters.