The dark mode still sucks with blinding contrast, but I still prefer that over light mode. But the functionality to have dark mode local to the app instead of tied to the system light/dark mode not only existed but was then removed.

Stop removing functionality. Change isn't good if it removes things that were already good.

e: this also makes this help page false https://help.twitch.tv/s/article/watching-twitch-on-ios-devices?language=en_US#LightAndDark