I don't have a good solution for you... but WOW. That is terrible.

Only thing I can think to do is to remove the "flat stock" riser piece.....reinstall the crown lower and have a shadow line affect. Meaning the cabinets will not go up against the ceiling. Aside from tearing down the house or having a ceiling gutted and releveled somehow (is that even doable?), live with it or do as I suggest.

like this:

Ps. Your crown color looks different a bit, maybe.

Pss. or caulk will be your best friend! You'll need to recaulk every year or so coz it will shrink during heating season!!!!!!

The Kitchen Place is right in making it appear as intentional as possible. Gap uniformity is critical plus paintable caulk. Uneven walls and ceilings are a fact of life. Most people will never notice and you’ll eventually forget the oops and enjoy the beauty of the space.

You need to fill that gap with something. Caulk might be the answer & paint it the same color as the ceiling.

A good drywall contractor can skim the ceiling and make that go away. We‘ve even used an additional 1/4” overlay in really low spots. Add the mesh tape to tie it all togerher and strengthen it, and you’ll be good to go. But you’ll still need caulk at the transition to deal with the normal seasonal movement.

My basement ceiling was not level & we filled the gaps with caulk & painted it the same as the ceiling. I was nervous & mad at first, but now you can't even tell.

If the gaps to be caulked are large, you should use some sort of backer . . . like old shoes.

(humor)

Thank you for the quick response! Good options given here and will look at more pictures, I'm not thrilled about the way the shadow line looks, but hey.. it's an option I can bring to the table.
We haven't checked the room above. He said that it may have been that the joist is uneven and wasn't caught during drywall process. I paid for the stacked cabinet option and feel robbed! He said, they will be feathering the gaps but the angle will still be there. insert cry emoji

Mud the ceiling down and repaint.

In the master bathroom above the ceiling in question, is there a large bathtub?

We had this problem during a remodel, and the contractor caught it. He had them add a new, level layer of drywall, without ripping out the old. We lost 5/8” of ceiling height, which was not a deal breaker.

Fix the ceiling.

There is no excuse for that except incompetence and/or lack of pride in their work. They need to level out the ceiling and re-do the crown and trim band, all the way around if necessary.

The gap for the crown really isn't the issue for me (Its relatively simple to fix). But, I just can't imagine the 3/4" + across the 3 foot cabinet that is out! That is really terrible assuming it is new build.

Cut a few small openings in the drywall big enough to get fingers in there so you can gently rock drywall to make it lose so it drops down to make it flush with the molding, Patch the holes. Before you cut holes, remove the trim from the recessed light, its looks like being close enough, and stick a flat bar between the housing and drywall and see if it can be done that way, if yes drop it down and put the trim back and if needed touch it up.

In most cases, this is a very quick fix.

Good luck

Not a suggestion here of a fix, those have been covered well. But it is good to figure out what caused it, as that is a large slope - too large it seems to be a framing mistake. Another commenter is zeroing in on it. With an upstairs bath it is common for plumbers to cut joists, leading to sag of that joist. Also, if you have a tub or shower drain the ptrap might sometimes stick down past the joist. Drywallers don't usually care about that stuff.