With the construction in progress, and not knowing the hood manufacturer installation instructions, it is difficult to tell if there is or will be a problem. Best to rely on the builder's answer. Is there anything else the builder has done to lose your trust in them?

Fume? Are you French? Not a word typically used in the US to describe a vent hood.

So your builder is installing an HVAC register (supply or return?) right in front of where your kitchen vent hood will be?

Doesn't seem like a good design choice. If it is a return register, you could be sending cooking fumes into your HVAC. If it is a supply register, you could be sending heated/cooled air right back out your hood vent if turned on.

And the register won't be pretty to look at in that very visible spot.

I would want it moved. Of course your builder will say it is perfectly fine!

Not French lol.. i have built 3 homes in the US… always referred to either way… lol 🤷🏽‍♀️

looks like it has the vent hood piping inside it….. here‘s a better pic….

An HVAC return isn't allowed in a kitchen per the International Residential Code. It could be to supply make up air for a vent hood with a capacity over 400 cfm. Ask your builder.

Look on the floor below it. Maybe it is noted there, the pot filer is.

Wait. What if what appears to be round ductwork is the pot filler?

The hood over the range is optional but regulated by the IRC in section M1503 “Domestic Cooking Exhaust Equipment”. A range hood or downdraft system would be served by an exhaust duct to a termination on an exterior wall or roof.
If makeup air is required, it is often added to the hvac system but not necessarily to the kitchen.

Charles- but can the make up air system be moved a couple of feet away as to not butt up against my future wood hood?

Sure. The location of a make up air inlet is the decision of the system designer. It can be located either in proximity to the range hood or at some distance--even as a supply to the HVAC system.

Im going to ask them to move it several feet away within the same framing line. Over the walkway or even over the island should not make a huge difference. should not affect turbulence in any meaningful way & will look much better in my high end kitchen. i have an email out to the owner. thank you!

"I have an email out to the owner."

Are not you the owner?

The owner of the home building company. I am contracted for the home. HVAC is coming tom

to find a better location.

I think the large area dedicated to the make up air is for maintenance access. You might ask what other options are available for locating the supply so it's not an "architectural feature" in your home. Of course, if your set of friends includes a lot of mechanical engineers, you might consider leaving it where it is as a cocktail party conversation starter.

I think we do not know. HVAC and hood venting and MUA all have rules and they can vary from place to place so yes you can ask to move parts but they still need to obey the code and honestly I would need to see the actual drawings of this finished . I will say a pot filler is one of the most useless things and in my experience the spot where water leaks seem to appear often. The issue is not the pot of cold water but the dumping of the pot of boiling water I always leave those out of my designs . IMO if this is a big issue for how you cook then a sink next to the range is a much better choice .

Prepare stories to tell at those cocktail parties such as: "We do not have space under our stairs, so our reluctantly adopted son lives in the hole in the ceiling we made for him. We have cleverly disguised it as a mechanical grill so nobody asks questions. He has not been good lately so we have hidden the ladder. Ignore any screaming or pounding you may hear."