I take it you didn’t watch Wandavision.Anyways, MoM felt way out of character for Wanda
she pretty much became a full blown serial killer, yes she was a war criminal in AoU and she killed a few people by accident in CW but here she went off the deep end
I guess Tony was right about having her arrested
She brainwashed an entire town in Wandavision. The loss off vision fucked her up and caused her to mentally break down to the point her powers went out of control. So she didn’t even know what she did at first but when she found out she refused to accept the reality and tried to keep everyone brainwashed up until the end where she gave up the fake family she had made. Kind of planting the seeds for what she became in this movie.
We saw in the movie the Darkhold exacerbated her already existing mental instability by corrupting/possessing her on top of that.
So not really out of character, as much as her negative thoughts and emotions being amplified. Just like the Evil Strange we saw in the movie who wanted to trade access to the Darkhold for the Alternate Universe Christine (heck it seemed to have been implied many versions of Doctor Strange couldn’t resist getting corrupted by the Darkhold and our Stephen was one of the few exceptions).
She even goes out of her way to destroy every Darkhold in the multiverse at the end because she finally realized the monster she had become and didn’t want to let anyone else fall to the Darkhold’s dark influence.
