HELP ME FIND THIS ANIME PLEASE

Okay so I actually never watched this anime, but it played in the background while I was in my living room and I watched a little bit so remember only one scene and a bit of the how it looked

Firstly, it was definitely on Netflix it might have been episode 7 but I'm not sure. (It could also be a movie but I really don't think it is) I believe The subtitles were in English (which isn't my first language) and I also THINK it wasn't in Japanese but in English, but I really can't know

so about the scene:

It was in a purpleish different planet or dimension that kinda looked like they were on a purple moon and there might have been an icky purple monster

There was this girl with long blonde hair she was PROBABLY wearing white clothes I thing and she was possed by something

At one point this black purple bubbles covered her and she was asleep and like a posessed villian (I think that was about halfway through)

There were other characters and I think they called her mom so she was their mom I don't remember much about them

Also while sleeping I think she got into like a robot thing or it was a monster but I could be making this up

I'm writing this in 4:30am because I am THAT desperate this has been making me absolutely crazy for years and I need to find it

(Also the kids who watched it were just visiting us and they're my step grandpa's grandchildren so there's no asking them)