Amazing that it takes so long for the patch to come, isn’t it? The 111 Firefox closes 13 partly high-risk security vulnerabilities… so, time is pressing…
I have to correct you with the comment about taking so long (It was actually there about 7 days ago), this package is maintained by one person in their spare time, just like @larryr who takes care of virtualbox. Project contributors (like myself) have other things going on, feel free to step up and assist the maintainer I’m sure it will be appreciated.
As @larryr indicated you can add the Mozilla repo… but if it doesn’t work, then a bug report is needed.