Few days ago, there was new version released (87). In certain situations, when silent upgrade had been made during using the browser it displays an "Oops, something went wrong" notification with a button to refresh. If you will close and reopen the Firefox the problem will vanish. It is less kind of crash but more likely as problem to free/monkeypatch resources.

I have run into the same problem on Linux but I have quite complicated Firefox configuration with at least few extra profiles (about:profiles).