JonnyT
First: iPhone 14 is using PWM, if you getting sick just looking at it for 5-10 mins, then you are affected. If you looked at it for more than 20-30 mins, you need to sleep to help your eyes rest and refresh your brain. It works for me.
Second: If you were exposed to PWM for longer periods like 2-3 hours, you would need more time to come back to your normal life, for me it's 1-3 days. Sometimes during this period any screen could give me eye strain.
Third: anything that casted or screenshots from that iPhone 14 cannot give you eye strain or nausea. It could be just a game gave you sickness, or your eyes didn't rest well after you were exposed to PWM.