Yes. ~/.mozilla. Its annoying.
You can fix it with a hack by putting a shell script in your path (before the original firefox) that consist of:
#!/bin/sh
HOME='/home/engywuck/.local/share/firefox' /usr/bin/firefox
Call that instead of the original firefox from now on. it will create the “librewolf” folder in ~/.local/share and chuck its junk in there.
Edit: This bug has been open for TWENTY YEARS.
Honestly ridiculous.
We can use dinit, s6, runit, and openrc.
There are more, but these are all top contenders.
I switched to dinit recently, it uses declarative service management (like systemd unit files). Very clean, fast, lightweight, and portable.