Who cut the counter that should have been fabricated to fit the wall and why do you have textured walls in a bathroom of all places.

Agree with above comment. Countertop should have been templated and fabricated to match the out of squared wall.

There isn't much you can do at this point but replace countertop. Plastering the wall to even the wall out is an option but you have a textured wall so most likely will need to skim coat all walls.

^.

Scribing and cutting the top to fit is my first choice, but it you don't have a grinder with a diamond blade, you'll get the same look with a drywall knife. Very little risk either way.

It should have had a filler designed there from the beginning. And the vanity should be shimmed level and square. And secured to the wall.

I don’t think the wall is uneven I think it’s the cut of the stone but I agree with Sophie

There was no laser template. Before I'd rip it apart? I'd stop staring at it. Even if you're on the "pot" across from it.. Some things, unless a 75k to 90 k bath? Not worth the angst. Sorry........it's true. Next time, make certain a laser is used, and DON'T let anyone out at install until thoroughly inspected. Every inch.

Have you checked to see if this cabinet is even mounted to the wall. Something is way out of kilter there. I think I would ask for countertop to be removed and cabinet reinstalled and secured, and make sure that it is level and straight. Once cabinet is level and square, the countertop may fit just fine. If not, then they need to replace it.

Claire and cat_ky:

Out of square walls are much more common and severe than out of square tops. They call it rough carpentry for a reason. It's an easy fix either way.