Charging a "Furnishing Fee" in Rent Controlled Apartment

[Will K]

I live in a rent controlled apartment, and my landlord charges a "furnished" fee of about 20% over the rent control "limit." Is this legal?

I was well aware of it when I signed the lease, and it was still an amazing deal and apartments go so quickly here anyone would have taken it, but I was wondering where this stands from a legal standpoint.

Seems like it would be a heavily used loophole to circumvent rent ceilings...fill the apartment with cheap furniture, then charge X amount over the rent ceiling as the "furnishing fee." Thoughts?