the.com/revolving door

means A rotating cylindrical doorway with wedge-shaped compartments that lets people pass in and out without ever opening the building to the outside air — and, figuratively, a job or institution people cycle through and back again.

from The physical door is an invention from the late 19th century, patented as a way to keep heat in and drafts out of buildings while still letting a steady stream of people through. The figurative sense — jumping between government and the industries it regulates, or a cycle of people endlessly entering and leaving the same role — grew naturally from the image: step in, spin around, end up facing the same direction you started, just with a different coat on.