Software drives the hardware, if Apple makes changes at the OS level it can have an effect. Take the Airpod Pro gen 1 for example, Apple continually adjusted the software which had a negative effect on the ANC according to many user reports.
Some have posted on Reddit and other forums that after upgrading to iOS 17, their LCD products like the iP11 were uncomfortable to view, similar to OLED eye strain. It’s anecdotal information, but was enough for me to not upgrade the OS until further reports as we can no longer downgrade back to 16.
Could be colour adjustments, refresh rates, animation changes, dithering etc. Just because it's an LCD iPhone doesn't mean OS changes have not introduced eye strain elements for the sensitive folk. It's also possible there have been no negative changes