Earlier quoted context omitted.
I use FF Android every day, including watching videos, and haven't noticed the "unstable garbage pile". Are you being hyperbolic?
On Firefox Nightly, I randomly get tabs that break and show an interactive version of the previously switched-to tab until you restart the browser, dragging a text handle to the left of a Hacker News comment crashes the entire browser, etc.
I used to have much more minor issues that are somewhat similar to what you describe, but they've been fixed for the last year or so. (I run Nightly all the time, on Linux, and generally have remarkably few issues with it.)