It’s pointless to argue whether this is deserved or not. Plenty of players became memes after their performance dipped, or when they found themselves in environments they don’t belong to, Torres, Fellaini, Lukaku just off the top of my head. It’s just the way it has always been in football and unless tomorrow you can magically take tribalism out of it and make people stop bantering, it’s not going away.
I would say though, the lack of empathy Maguire evokes from his own fans, to some extent, is out of his control. The guy is clearly struggling for confidence but as a fanbase we are used to people responding to scandal/widespread criticisms with excellence on the pitch, so the perceived shrinking violet act is less forgivable.