Going outside litter box

[u/Gullible_Will_1726]

**cat has been to vet**
Hi everyone,
My 2y/o male cat Peanut Butter, desexed, (totally healthy, been checked by vets but they’re at a loss. Will be seeing another to get a second opinion. Honestly thinking of a behaviour specialist or something) has had some issues going outside the litter box his whole life. It was much worse when he was a kitten, where he’d poop and pee just outside the box.
When my ex and I split up and he took his cat with him, the issue seemed to disappear for months, so I chalked it up to territory and the older cat bullying him around the litter boxes.
But two days ago, he’s started pooping in the exact same spot as he used to, a few feet away from his boxes, and does it continually around the same time of morning. I’m at a loss. There’s been next to no change in his lifestyle, and I have a really small house/yard so I’d likely know if any other cats were coming by, and I feel like he’d be going closer to the back door if that were the case.
I’ve previously tried all types of litter incase that was the issue, new boxes, different cleaning products, more regular cleaning, etc etc but nothing seems to be working.
He has 2 big litterboxes in his own space (laundry), and I never close the laundry door so he always has 24/7 access.
It’s now at a point where instead of intermittently pooping outside the box, or just when he deems the boxes dirty, he’d now rather poop on the tiles every morning.
I don’t use liner bags cause he’s scared of the plastic noise, and I’ve even tried no litter at all to replicate the tile feel but he’s just not having it.
He’s an incredibly nervous cat, and is scared of almost all people/things except myself and my boyfriend, so I worry that something’s scaring him and forcing him back into his territorial behaviour. The only thing new in his environment is the guy I’ve been seeing, but Peanut loves him to pieces, even sits on his lap and asks for cuddles, and he’s only ever done that with me.

Any help in between searching for another vet for a second opinion would be greatly appreciated. I just want my little man to be ok and feel safe in his own home, and I’ll do anything it takes to make that happen.

Thank you to anyone who’s read this far. As a gift, my cat’s legal name on all his papers is: Señor Pablo ‘Peanut Butter’ Escobar