I am facing the same issue with my two cats at the moment. We do have street cats that I have been feeding for almost 4 years, but it has just started now. I mean, my cats always saw and smelled them. Even more, I walk my cat Spicy regularly on a leash and sometimes let her walk alone, but it's only supervised. I never let her out of my sight. We live in a pretty safe area near the park, with many trees and greenery. I let the other kitty, Tigra, roam independently because she becomes desperate when I say "No". She has a different personality, so there was no way to train her leash walking. But, again, I know where she spends time, and she always comes back home safe and happy. But the point is, with other cats and smells around, they have started marking their territory just recently. Tigra sprays on the chair in the kitchen, and Spicy started to spray on my bed. That really sucks. They are both female neutered cats. The only thing you can do is try different ways to stop that. Ask CharGPT ))). I purchased an enzymatic cleaner. So every time I find a urine spot, I spray on it and it helps. Sceptical, I was, but it really destroys the smell, not just covers. By the way, it's HG odour eliminator. Only then do I wash the bed cover in the washing machine. Since my cats "misbehave" when I am at work and early in the morning while I'm asleep, I've decided to buy a waterproof pet blanket. I've ordered it from Temu. At the same rate, I've limited their access to my bedroom. It's closed when I am not home. Well, they are confused, but they can only blame themselves. It can be anything triggering the problem: cats outside or stress. The two don't get along. No fight, but definitely disliking each other. I am also waiting for a cat-calming spray to arrive soon. Hopefully, the lavender aroma works miracles. We'll see. But the first thing I did before all these, I took Spicy and Tigra to the vet for a full medical checkup. No kidney problems or anything. Thank God, they are healthy cats. I know it's really hard to deal with the cat urine issues. I guess this is why so many kitties end up on the streets. Sadly. I love my pets and will do my best to solve the problem.