I confirm what Seagull said. A "good" monitor can turn "bad" depending on which computer is connected to it.
As many others on this forum, historically I have encountered more issues with devices mounting Intel graphic cards.
Unfortunately, I also experienced the effects of software updates rendering my Android phone and my laptops (Windows and Mac) nearly unusable, like, before the update I could look at them for hours without pain, and afterwards few seconds would be enough to cause intense eye and neck pain.
As to your question on the IPhones, I was lent for 2 weeks an Iphone 6s an year ago. I found it unpleasant at the start but I could handle it after a while. I do not recall which OS version was installed. I wonder what would have happened had I kept the phone and downloaded updates?
When the 7, 8 and X came out, I tested them and immediately developed long-lasting discomfort. No way I could use them. Since then I only took a look at the Iphone XS in October and, as a couple of other people on this forum, I surprisingly found it eye-friendly. However, I am cautious about a 10 minute test, also considering that my eyes were already sore by other devices, and I did not investigate further considering the price of the toy. You may want to read what tfouto wrote about it at https://ledstrain.org/d/21-usable-smartphones/850 and test it yourself. Good luck!