This is “gravy” in the same way American squirt cheese is “cheese” in that certain people will call it that. But its categorically a completely different thing.
It’s a bechamel, friend. You are fool who doesn’t understand food. You probably boil everything you don’t microwave.
It’s a roux with some fucking liquid added, which is exactly what you do to make any gravy, regardless of the language root of bechamel. Stop being so goddamn pedantic.