>>117617539I wouldn't, because I've been IN a toxic friendship. Toxic relationships imply that they make everyone in them miserable and both parties worse people to a very significant degree. Their relationship could have become toxic LATER down the road if it kept going the way it was, but they got isekai'd before that happened.
If their relationship was outright toxic in the way you are characterizing, Sasha wouldn't have given a fifth of the shits she did about Anne in her S1 appearances. The problem with their relationship came from two sides- Sasha (like many teenagers) thought she was hip and worldly and the smoothest operator in the room, so OF COURSE she knows better than her friends. Anne, like many teenagers, girls ESPECIALLY, is clearly very approval-seeking and afraid of social rejection. A functional dynamic? No. A toxic one? Also no, unless you want to assume every flashback scene between the two of them was, like, the single best day of their friendship.
It was only once Sasha spent three months with the toads getting swamp gas blown up her ass about might-is-right and how the weak aren't really people in an environment where she got constant validation that she was the smartest person ever that it got to the point where Sasha expected Anne to just let some old man fucking die.
Besides,
you're still assuming Anne is the VICTIM in the Marcy-Anne dysfunctional friendship dynamic, whereas I think it'll work better in the greater structure of the story if Anne was the one leading their dynamic. 
