As stated above all powdercoated steel frames will rust under the lacquer.
When painting using wet paint the primer is usually zinc based so the zinc will act as the sacrificial metal which will stop rusting.
Zinc primer cannot be made to be clear, which is why you don’t tend to see wet painted clearcoated frames. There are clearcoat primers which are marketted as having corrosion protection but i have no idea how these work.
I had a clear powdercoated frame, took about a month before a massive rusty handprint appeared on the downtube (moisture from transferring frame from sandblaster to powdercoat booth). It looked rubbish.