A 21-year-old bug report requesting support of the XDG base directory specification is finally being addressed by Firefox. The Firefox 147 release should respect this XDG specification where files should be located within the home directory of Linux users.
The XDG base directory specification states that application data files, configuration files, cached assets, and other files and file formats must be located within the user’s home directory and XDG environment variables to access those locations. As of today Firefox has located all the files below ~/.mozilla instead of like ~/.config And ~/.local/share,
This bug report was opened in September 2004 to support the FreeDesktop.org XDG base directory specification.
Support for this specification and associated commits was merged this morning.
In turn this long-open bug is now closed and Firefox 147 should finally be the version supporting the XDG base directory specification to integrate more well with other Linux apps.