Cat pooing on the floor

[Prawncocktail24]

I have an elderly cat who loves the outdoors. He's always used his litter box without issue when indoors. He likes to stay outside over night, but he's had some of his fur shaved off at the vets for a procedure so I kept him in last night as I was worried about him getting cold. He's had a wee in his litter box over night but pooed on the floor for some reason. No where near the litter box, so it isn't like he's just missed. He's never done this before. Only saw the vet yesterday and despite his age and hyperthyroidism he's fairly fit and well. Is this likely to be stress because I've made him stay indoors when he'd prefer to be outside? I don't want him upset at being kept inside but I don't want him freezing either, just looking for some advice if anyone has any please x

How big is the litter tray? It could be that because he did his wee in the tray he didn't want to use it for the poo. Try two litter boxes.

Also, how much has he been shaved? Unless he's totally bald I would still let him out. If he is used to his freedom he might prefer to do his business outside. If he is feeling cold he will come in himself.

Hi, thanks for replying, he's had quite a lot shaved off his side and his belly but I've started letting him out because he's happier outside, I'm just bringing him at night until his fur is a bit thicker. It seems the pooing on the floor was a one off as he's been going in his litter box since, so I think he was just a bit stressed after the vets combined with being kept in when he'd rather be out.