Firefox outdated, new version came out three days ago and is supposed to fix the add-on bug.
Current version in our repositories
New version available upstream
As I'm sure you're aware, add-ons have stopped working, including vital ones like uBlock Origin. This is said to've been fixed in the latest version, which came out three days ago.
To upload designs, you'll need to enable LFS and have admin enable hashed storage. More information