We think we have one kitty that has some sort of urinary issue as he insists on standing up to pee and makes a mess of the litter box. He is not in pain, but we worry.
I’ve had 2 cats with urinary crystals and they didn’t show signs of pain until almost completely obstructed. Cats seem programmed to be stoic - you can’t show weakness in the wild.
I know it’s expensive, but a vet can quickly check by getting a urine sample. You might have to leave kitty there some time though - my girl was stubborn and held it for hours and hours!
Any change in litter box habits can indicate a problem - some times they think the box is the problem and try to go else where. My male flung litter all over, I guess he thought it was the litter’s fault.