Remember the old computers? About 20 years ago I used to sell paper holders made out of plastic, one of the colours was named "Computer White". I don't know if it would ever get the wee-burned shade in sunlight like the monitor housings did, though. Anyhow, the plastic parts of computers seemed to yellow faster than the painted steel, partially of course because usually the case was hidden into a doorless cabinet in the desk, leaving only the plastic front affected to sunlight.
The question is, how much difference is there in polyurethane paint compared to the ABS? Will it yellow similarly in sunlight/UV rays? This blog says it will: https://www.bowerpowerblog.com/solution-yellowing-polyurethane-master-bed-makeover/