What is this? (Paint related)

The reason it happened is the paint dried before "flowing out" either too fast of a reducer or the temp was high or your spray was incorrect, to high air pressure or to far away from surface. I would start over, take the whole car back down to flat paint with 400 and reshoot with the slowest reducer available. If you try to block and buff you are probably going to go thru the paint on the edges anyway. Repainting will be easier. Use base coat/clearcoat if you can. Blocking and buffing clear is much safer.