So, is Joker not a villain, then?
Are we using the term in the colloquial comics sense of "person who does a great deal of harm," or in the literary sense of "person who opposes the main character"?
I think that, even as we're enjoying some light popcorn cinema, we should be attentive to the fact that morality isn't black and white, and that categorizing people into good and bad is a simplistic mindset that has led to many people permitting great harm to others.
Now, in nearly every story of the Joker, he's got a twisted sense of how the world should work, but he knows what he's doing is hurting people, and he almost never cares. He can be both ill from mental trauma and be intentional and callous in the harm he causes.
Wanda, at least in the MCU, had been presented in a different light. She's also been traumatized, but she never revels in hurting people. In Wanadavision she does, yes, seem to be in denial that what she's doing is hurting people, and tries to rationalize what she's doing.
She just wants to be left alone to be happy, and she's willfully oblivious to the harm she's causing. It honestly could have been tweaked a bit into a metaphor for consumerism selling a happy lie of a good life while ignoring the harm to society and the environment. But I digress.
She nearly snaps out of it when Vision confronts her about it in the 80s episode, and she seems to be trying to parse the cognitive dissonance, but then Agatha sends Ralph to draw her back into a comforting delusion.
And eventually she does acknowledge she needs to free the people in the hex, and she makes what I saw as a heroic sacrifice to do the right thing, albeit horribly late.
. . .
And then the next time we meet her, she's not struggling at all. She's not in denial. There's no glimmer that her original mind is somehow being controlled by the Darkhold.
Instead, Wanda has gone full, exultant villain.
The writers didn't do the work to make that transition compelling.