demonx

There is this white fill around the bumper area and also on the rear spoiler lip.

I'm having trouble telling if it is factory or was "painter bubba's" effort to hide something nasty.

There was paint cracking around the area and you can see here where I've circled the fill has cracked also.

Either way I'm going to have to repair the area with something. What type of fill/bog can I use that can be sprayed with polyester sealer without cause for future issues?

I have uncovered the same situation on the rear spoiler where the same white fill is hiding "something" I'm yet to unwrap.

zwede

Not factory, probably a fender bender at some time. White stuff is "bondo" and you need to carefully remove all of it so you can see what you got. Once you have only fiberglass, you want to grind it down, and then build up with mat & resin.