Cat owners - do you think this cat is doing this to be annoying or is there something wrong?

4 weeks ago my partner moved his cat to our place, where my cat lives with us. The first week of the move, no issues. His cat was going toilet in the litter boxes just fine. But since the second week, his cat won’t pee in the litter boxes anymore and instead chooses the carpet or the kitchen floors instead. I’m tired of scrubbing the carpets and mopping the kitchen. The carpet that he pees on and the kitchen is further away than the litter boxes, so it makes me unsure if it’s a bladder issue/infection, and makes me wonder if he’s just doing it to be a pain in the a** or doing it for attention, especially since he always chooses the exact same spots to do it on, rather than it happening in random areas of the house. His cat is 14 years old and fixed/neutered, if that’s helpful. I don’t know whether to take him to the vet and waste $200 incase it’s just attention seeking behaviour.
Cat owners - do you think this cat is doing this to be annoying or is there something wrong?
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