Have people complaining of eyestrain from "light mode" considered checking their display brightness? Displays should match the brightness of their backgrounds, or in general somewhere around 100–150 cd/m² (aka 100–150 nits). Most monitors are capable of going much brighter than this, and really should not be used that way, because it tends to... cause eyestrain.

I have brightness on high since every other application and website I use has a dark mode and I get blinded when switching to Hacker News.

Effective luminosity isn't just a function of how much light the device can output at a given setting but also how much light is being blocked or is otherwise not emitted by the image being displayed. By making the background dark and the relatively sparse text light, you can lower overall light output while preserving more of the contrast.

And low contrast can also cause eye strain.

I find light mode painful even on minimum brightness.