She was did dirty, they reduced her from a complex and tridimensional character always torn between being a "hero that doesn't want to hurt people" and a "person who lost so much and would do anything to have that back" to a very bidimensional and flat character that is "evil because she's a witch, and she uses dark magic".

It didn't give the character justice at all, and instead of evolving her they devolved her and make her repeat the EXACT same arc she had in Wandavision. It's not about her becoming mad/corrupted that annoys me but how they explain it. "I'm not a monster, I'm just a mother". It would've been so much more better and even more tragic if we saw the "heroic" side of wanda trying to fight back against the Scarlet Witch "selfishness" and corruption, even if it meant she'd fall eventually and became mad. But at least it would've given her character a lot more depth than they gave her in the movie.