I mean it, though. Fandom at large seems to have a problem with recognizing characters as morally grey, not just the Attack on Titan fandom.
And even more than that, they have a problem with realizing that it’s okay to acknowledge a character’s flaws as a person and still like them.
It’s the same tendency that creates the trend of people woobifying villains. There’s nothing wrong with liking villains. Evil is sexy, villains are often interesting characters in their own right, and more often than not, villains aren’t one-dimensional moustache-twirling cardboard cutouts. They can be sympathetic and morally ambiguous. But it’s so common for these traits to be spun into “actually this character is 100% a good person and should be loved and pitied and everyone who opposes them is the real villain”, when there’s no need in the first place. A villain can still be a villain and be sympathetic.
And a good guy can still be a good guy even when they’re morally grey and ambiguous. Not everything they do needs to smell like roses for you to like them.
I don’t know why this is hard. You are allowed to like a character who isn’t 100% good. A character you like does not have to be 100% good for you to like them. Don’t bend over backwards to recontextualize or selectively ignore their actions.