Originally Posted by Scrambler82

Isn’t that the OP pic ?

Anyway, Plastic is not an absolute solid material so in turn it will absorb paint, to some extent, differently along the piece, that is why you see a variation in the finished color and that is why there are Primers or Primer Sealers.

If and when you do it again, try this… (everyone has an opinion, you know the saying)
Remove the paint, clean the flares, spray with an Adhesion Promoter (DuPont makes one in Rattle Can) after setting the spec’d time frame to dry, spray with a good primer.
How to pick the primer is easy, if the surface id smooth then a standard Primer is OK , if there are imperfections in the surface you might want to try a Primer Filler.
Primer Fillers require additional prep work, sand wipe clean, etc… but the results are what you are looking for so a little more work may be all it will take.
After getting a surface that is a smooth and clean as you want, and hopefully you did not break through the primed surface, spray with the color you want.
Stick to the same manufacturer of paint products to assure compatibility and use the adhesion promoter.