Changing bulb in shower ceiling light fixture
Are you sure the whole fixture is spinning? The type of light rated for wet locations used to have a rubber seal and screw fittings. Most of the time the "jelly jar" type fixtures the glass needed to be unscrewed (and they do get stuck and feel like they are going to break). There were some the metal ring was threaded holding the glass in place. So it could be that you need to unscrew the ring. Also check the ring for a small set screw to lock the Glass / ring in place.