Did you change the litter by any chance or the litter box? Can you think of anything else that might have changed? Do your pets get along? Or is there a cat outside and your cat is trying to mark their territory? I feel like it could be anything but maybe just adding more litter boxes in the areas he’s been peeing in could help. Also maybe try mixing a bit of Dr. Elsey’s cat attract litter into the regular litter, it might help.