I just moved into a new house, and it has a weird step in the bottom of the closet, that is covered in carpet. I’ve seen this before, and it could just be coincidence, but is there possibly a weird architecture or design reason for this, or is it just a quirk?
Could it be hiding pipes? Is there a sink or bath behind this closet?
I’m guessing this is it. Pipes or vents.
Someone else mentioned HVAC and that makes sense with where the air filter is installed. Now, why the carpet.
It is a linen closet, but all of the plumbing should be… Not there. It’s opposite the hall from the bathroom, and the plumbing fixtures in the bathroom are on the furthest wall, it wouldn’t make sense, at least to me.