Ah, thanks for letting me know!
I may have found a fix. I previously applied CSS `overscroll-behavior: contain` on <body>, it seems it also needs to be set on <html> (see https://developer.mozilla.org/en-US/docs/Web/CSS/overscroll-... and https://stackoverflow.com/a/60565197).
I pushed that (supposed) fix, please let me know if that solves the issue for you (you may need to “refresh” by launching-quitting-relaunching the app.)
If not, please tell me what Android version and browser you are using, so that I can investigate more.