The unfortunate trend is people producing otherwise useful educational Youtube content (particularly developers) in dark mode. They surely don't realize they are losing some portion of their audience due to any of a few reasons (not the least of which is the audience who actually works outside sometimes!)

I've seen this more and more, but I wish sites would provide a way to switch themes. For example, the Ghost blog default theme follows your device preference, but AFAIK there's no way to toggle to light mode, which is quite annoying considering how common it is.