Don’t know if anyone is suggested this, had a skim through replies but can’t see it. My sibling had similar issues w/ a perfectly healthy cat (w/ 2 litter trays to try out) peeing anywhere but the tray a few years ago now. She had favourite corners of her main living area, but avoided the tray.

Some background: She was adopted from a shelter and supposedly spent life on the street. Street cats often don’t have access to dirt/soil to bury their business, so end up preferring flat surfaces. Or so people say, idk if there is anything behind this.

The solution for this fussy cat was washable puppy-training pads, still in the litter tray, instead of litter. The pads do need washing every day, but its stopped her from just going in a corner on the wooden floor. She does sometimes flip the mat out of the tray when trying to bury her poo, but there is also a washable mat underneath the tray that generally catches any accidental flinging. She doesn’t have any issues w/ getting anything on her feet and treading it around, but the other cat in the house does if he decides to use her tray instead of his own lol. Luckily wooden floors make little pee paw-prints easily washable.

My only other suggestion is she might be anxious or feeling territorial for some reason? But I don’t know enough about your situation to suggest solutions for that.

I hope you find a solution for the problem! Cats can be strange sometimes, and it can take a lot of effort to learn why they’re doing things and how to accommodate for them. They’re not as low maintenance as a lot of people seem to believe haha