Can we agree to wait until the end before we decide if the work is fascist or not?
If Eren wins, the world gets genocides and all is portrayed as a happy ending. Then yes, maybe AoT is, indeed, a fascist work.
But if Eren is stopped and genocide does not happen, and it is portrayed as a good thing, then no, how can AoT be portrayed as a fascist work?
What is worth of debate, however, is seeing people online fully agreeing with Eren if they believe there is no final twist in his plan. It is one thing to trust that Eren will pull out a Lelouch or a Sasuke or another twist. It is another to trust that his genocide is morally justifiable (I am not accusing people who wants the world genocide for the sake of story itself, btw)