You can certainly ask him to fix this but be prepared for some pushback. He ma need to redo some waterproofing. The tie in waterproofing from the wall to the niche may become compromised. By the way what was the waterproofing used as the first pic appears to be showing bare cement board?

@millworkman Thanks for your response.

In this case, sounds like he has to redo everything. I don't want to go through the trouble. I guess I'll just have to live with it.

For waterproofing, we put paper behind hardiebacker and we taped hardiebacker joints then applied thinset. For the tub bathroom, we added one more step which was flashing the tub to the wall.

What kind of paper behind the Hardie? Hardie is not waterproof, hopefully held up properly off the pan as Hardie is known to wick water badly.

I’d ask about it. That would bug me every shower or bath. And I hate to eve say this, but the way he laid the tiles out so the pattern is a consistent diagonal stripe look would not work for me. I don’t think he mixed them up very well. Sorry.