I have an Iphone XR and Iphone 8 running IOS 16.4 and iphone 11 running 16.5. Iphone 8 works really well with no eye strain, headaches or dizziness , same for XR but iphone 11 with IOS 16.5 gives some eye strain and mild motion symptoms, very mild though. I tried several iphones from X, XS max to 12 and all gave me terrible symptoms with few minutes of use.
Used Iphone 8 plus in past and that was smooth for eyes too. A bit difficult to draw a conclusion but I feel iPhone 8 should be smooth on eyes but better to try it out as each persons symptoms are different.