I need help fast about my kittens :( ?

-So we had these two female kittens for less than a month now. One of them was already spayed and the other one got spayed today. They were very friendly just a moment ago and in general. Used to fight sometimes but they sleep together and clean each other etc. So after we brought the second one home after the surgery her sister (they're siblings) started hissing at her and they're both very scared of each other right now. I'm scared as well because I've never saw one our kittens do this to anyone before. Can someone please tell why the hell is her sister acting like this? What happened? Is it like her smell changed because she spent 5 hours in the clinic and that's why her sister didn't recognize her?聽

Your help would be really appreciated.聽

Thank you so much.聽she probably smells like the animal hospital, a place that the other kitten isn't a fan of since her surgery, they will get over it with a little time. honestly though for now it might be a good thing that they are avoiding each other right now because the kitten who just had the surgery will be able to rest and wont pull out her stitches or whatever playing. if your worried that they might hurt each other it might be a good idea to shut the one who just had the surgery in a bathroom or somewhere away from the other cat. my cats did the same thing, it took a month and then they got over it :) hope that helpsMany times cats don't like the vet, so when another cat comes home smelling like the vet, they don't want anything to do with them! Once the "smelly" cat gets their usual scent back, they should be back to normal:)
I have two male cats and this happened when they both got neutered. After a few days they both got used to each other again. I think it was the smell of all the other animals from the vets office
They need 2 b in a room 2gether so they can b like they were