Firefox, upon opening with a link passed as a parameter (clicking a link in some other application which opens up the default browser to that URL), freezes completely and prevents me from manually opening a new instance, saying that another Firefox instance is already running. Opening a system monitor shows a running Firefox process, pointing to the previously clicked URL, but does not respond at all. CPU and RAM usage are both 0 for this process, so it's likely not even doing anything. Not even a SIGTERM will terminate the process, I have to throw at least two SIGKILLs at the process for it to die. Why is this a thing? I've been using this browser on this exact same system for almost a year now, this was never a problem before.

OS: Arch Linux Kernel: Linux, 5.9.14-arch1-1 Firefox Version: 84.0.1