this happened to my SIL at her lake cottage - she found a terrific vintage basket and removed part of it so it could sit over/around the exhaust pipe, it looks like a nice basket on top of the cabinets, you'd never know the pipe was there

Oh, that's unfortunate! I'm generally not a fan of stuff on top of upper cabinets, but la_la Girl's suggestion is a probably what I would do.

The other option is to frame out a rectangle going to the ceiling, covered in drywall.

Or..have a stainless steel wrap made to look as if the vent goes to the ceiling..another thing that always encourages more opinions is a picture from much further back..giving a better idea how big the kitchen is..for proportional purposes…but …of course… that may also evoke more comments about adding a backsplash..etc..etc.

Add a simple cove crown moulding?

Crown moulding may be a challenge with all those odd angles..never mind finding wood that will match..or is even wide enough to serve your purpose..

Have a friend with the same problem who covered a box with Marimekko type wrapping paper and sat it on top of the cupboard. I always thought it was decorative until recently she revealed the pipe.

Just frame around it with a drywall “chase” that goes to the ceiling. Paint the wall color. It will disappear and be fine.

Why are we viewing this from above? Is there a loft or stairway?

I assumed they were standing on a chair so we could see how it comes out of the cabinet?

palimpsest, when (and if) we ever vent our range hood through the vaulted ceiling in our kitchen (it's an inside wall, so going through the wall is not an option), this is exactly what I plan to do. It seems to least obtrusive to me.

I agree with the stainless hood extensin placed there it would look right and no other stuff needed . I sure would not try to balance some basket there how would that cover it . You can get hood extension pieces easily or if you have a metal working shop it can be built for less than $200 Next time you have a dilemma post the pic from much further back and also taken from how this space is viewed not from the ceiling .

Simply cover with drywall, doesn't have to go up to the ceiling just a box or simply surround. Chances are you won't see from standing on the floor below.

Same color paint as the drywall.

Your cabinet crown molding is square I would put a row of full depth cabinet up there and finish it from bottom add some lights to illuminate your countertops you can also take your crown moldings out- if this seems out of budget you can do the same thing maybe half cabinet half just fixed panels also if this is steel out of budget- you can make a bulk head but flush it with your uppers then painted

Box it out with drywall (to the ceiling) Quick and easy. will look like they finished the job.

You can order a range hood extension chimney piece. Wayfair has them, likely the big box stores do as well.

Range Hood Chimney Extension.

This or the drywall ideas above would either make it look intentional, or make it fade into the surroundings.