I was doing an inspection this afternoon and came across aluminum DV Liner through a closet. It was unprotected I was told this was a legal install by the company that installed it. I believe that it is not! Please help.

I was doing an inspection this afternoon and came across aluminum DV Liner through a closet. It was unprotected I was told this was a legal install by the company that installed it. I believe that it is not! Please help.

What is DV?
Sorry Direct Vent Gas Fireplace.
I would think that vent would get kinda hot when the FP was on.
I don’t know for sure if its right or wrong but I would definitely point it out!
Cheers
Looks like this product
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Warning: This product is not a Type-B gas vent and should not be used in applications where Type-gas vents are required.
Clearance: One-inch to combustible, do not enclose, do not pass through walls, floors, or ceilings.