As it says in the title. Scrolling up moves it back to the bottom, but at a certain threshold it just seems to get misplaced. Attached is a screenshot of it happening here on meta.
We only support the native browser on each platform, for Android that is Chrome. Firefox is very quirky on Android.
Interestingly, this is the only issue I’ve run into in Discourse on Firefox; otherwise, it’s flawless and actually performs better for me than Chrome does.
Happy for you to close this as “won’t fix”.