p.s. I had previously happily removed “jumping spot” artifacts by placing a copy of the keyed clip above the same keyed clip, this however worsened the other noise I mentioned between the actors and around her hair, etc. Here’s how it looks with only one keyed clip. The noise on the sky is less but the spots on his head are now visible.
The green screen removal was made with 4K Canon footage in Ae on a MSI laptop. Thanks!