My Safari browser extension StopTheMadness Mobile has been updated to version 15.1 today in the iOS App Store.
The previous version 15.0 introduced the video speed website option, which allows you to speed up or slow down web videos automatically. I said that using the "Video speed" option with YouTube also requires the "Fixed speed" option, because YouTube is naughty and tries to undo video speed changes. With today's update, I've worked around that problem, and you no longer need to enable "Fixed speed" on YouTube.
Today's update also improves the "Hide some app banners" website option on Instagram, hiding some more "get the app" banners that prevent you from using Instagram in Safari.