The good news is that it's PVC trim so you shouldn't experience any rot issues.
The bad news is that's it's PVC trim so paint doesn't adhere to it easily.
Properly, the trim should have been:
- Washed: by hand or light pressure-washing
- Let dry
- Scoured with 220 grit sandpaper so that paint can better adhere to it
- I believe the same effect can be achieved by rubbing down the surface with isopropyl alcohol
- If sanding then rinse off the dust and let dry
- On a shady day:
- Painted with a PVC paint primer which accepts latex paint
- Painted with a high quality exterior latex paint of the desired color
As you might have guessed by now you will have to get all of the paint removed so that you can perform step #3.
The shady day is important because in direct sunlight the paint will dry too fast and not properly bond to the substrate.