Cat peeing on sofa

[Iamme2023]

I'm literally at my wits end, we have 4 cats the youngest is 2 years old and last he year ended up with cystitis.
Basically he ended up stressed out as at our vet check he had dirty ears and the vet was adamant we needed to clean them. He absolutely hated it and this triggered the cystitis.
He was peeing on the sofa, carpet and bed, it stunk but we knew it wasn't his fault and it settled a bit so I replaced the sofa and carpet as no matter what I did it still smelt.
We started him on cystease and zykleene once he'd finished his antibiotics and painkillers to try and chill him
We have five litter trays, both covered and uncovered with different types of litter in different areas around the house. water bowls on every level of the house and a water fountain but he hates it and regularly tips it over and floods the upside or kitchen.
We have him on a mainly wet food diet as he can be a bit fussy and his dry is thrive/applaws.
We have loads of beds, hiding spaces and I've just spent a fortune on a rhr cat tree for them which he loves.
We spent a fortune at the vets last year and there answer was well he's obviously unhappy you just need to re-home him as he obviously doesn't like the other cats
We thought we'd cracked it as we started feeding him on the sofa where he was peeing, this sofa has removable covers and I'm using puppy pads to stop pee soaking into the sofa, we use enzyme remover when he pees on the sofa.
Recently he's started peeing on the sofa again after months of not, it's really getting me down I don't know what else to try, but I'm not rehoming him as otherwise he seems happy.
He does use the litter trays for peeing it's just once we're in bed at some point overnight/early morning he pees on the sofa, it's a huge pee not a cystitis type pee either
Anything anyone can think of that I've not tried
Photo of the culprit laid in the window, he obviously hates our other cats so much he happily will lay with them

How strange - we had exactly the same problem with our cat - the midnight mega pee on the sofa. The main thing we tried that worked was putting out physical obstacles on the sofa before we went to bed - we used upturned dinner plates and rather meanly, some of those plastic cat spikes they sell to stop cats peeing in flower beds. I also went through an exhausting stage of waking up when I heard him hop downstairs for his midnight pee, as I found if I could catch him squatting and grab him and dump him in his litter, then he would just pee in the litter as normal and go back to bed. It did break the habit eventually but be warned he may just transfer to another location - ours chose under the bed 😐 Oh and avoid puppy pads as apparently they contain an enzyme just encourages animals to pee on them so you may be stuck with them for life!
Note: All of the advice above I got from wiser MNers !

Even though this sounds like behavioral marking, chronic or low-grade pain (bladder, spine, joints) can trigger episodes. Was a full urinary panel and maybe ultrasound ever done? Some cats have feline idiopathic cystitis that flares unpredictably.
Regarding food: Applaws/Thrive can be too low in moisture or not ideal long-term. Is the wet food high quality, i.e. without grains and sugar?

We had this when other neighbourhood cats were coming into the garden - started peeing indoors on sofa and beds.

we just have to keep doors shut now and he seems to happily use litter tray - even though he did use it before he still chose to ‘mark’ other places.

so frustrating - and not much help sorry! But feel your pain! X

Do your cats have outside access?
If not - letting them out may reduce stress levels.

Cats shouldn’t be living cooped up indoors with other cats - let them out.

Yes he had bloods, urine tests, ultrasound everything done. He eats untamed wet food, he can go ages without any wees on the sofa and then he does it for days
The vet has said physically there is nothing wrong with him.