I’d say just about every permutation is possible, but I was speaking only to a specific case. You may have misunderstood me, as revealed by this statement: “there’s no point just observing a phenomenon — formerly beautiful women seem less competent as they age”.
In the case I am presenting, they are equally competent throughout their career but treated as more competent (often by male superiors who know they are not) even though everyone but her is quite aware. This can have negative consequences for her later in her career. It is not that others see her as less competent as she ages. It is that she perceives it that way. Everyone else already knew.
I’m sure all the other examples you give also occur.