is all this paint from one job ...or old and new?
I can't tell what I am looking at there but it looks like a drill hole in two layers of filler
it is nearly impossible to feather out a small area like that and get it completely smooth. what grade of paper are you using? id use 240 grit on a da and feather it out as much as possible.
then 3 coats of high build primer and block that back with a guide coat will get it perfect.
without high build primer you will never lose the edge.
cant say ive seen this effect if all the paint was done at same time
yes if its old paint with new on top it would do it