Honestly, I think it’s great: if it annoys people enough, they will move out from Chrome and install Firefox (or one of its forks) with good extensions for blocking ads on YouTube. It seems to be the only solution to break the monopoly of Google on browsers. So go Google, I believe in you!

Pop!OS is a pretty stable distro, so there shouldn’t be any dependencies problem: you usually have that on arch or arch based distros, even if it’s quite rare. Have you ever uninstalled Firefox and reinstalled it but without some of its dependencies? Or ignored a package it asked you to install with it afterwards? If not, maybe it’s just an update that went wrong, like the PC shut down during an update or something. So update your system, uninstall firefox and reinstall. Your data stored in your home directory (in .mozilla, a hidden folder) like your history, extensions, opened tabs, should be conserved, even if you use apt purge.

Unless it’s a RAM filling issue, because you would have too little RAM, and even then, the entire OS crashing and not just Firefox would be very unlikely, I don’t see any reason for it to crash your entire OS. Regardless, there are Firefox forks that use much much less RAM. You’re using Windows, Mac or Linux first? Try to uninstall, clean everything and reinstall with a new profile, it may work, who knows. If not, then it has to be your OS.