Does anyone else not want agatha to be the big bad? It's a long shot, but it's possible she's being possessed by as-of-yet unseen extra-dimensional beings like mephisto; when she asked Wanda if she was alright it could have been a case of her true, undominated personality trying to assert itself. Realistically, the more likely explanation is foxsilver momentarily wresting a few seconds of control back from agnes to empathize with wanda.
I've also read a theory somewhere that agnes can only focus her whammy on one superpowered being at a time, which explains why pietro is free to run around and sneak up on monica while agatha is mindscrewing wanda in the basement.
Also, last week's ad references the nexus of all realities from the comic books. I have a hunch it's gonna figure heavily in dr strange 2.
...she's feeding off of Wanda...
Yeah, I figured as much seeing as episode 6's ad makes mention of "snacking on yo' magic". Either it's Agnes herself helping herself to Wanda's latent chaos magic or someone higher up than her is turning westview into an all-you-can-eat buffet.