Ubuntu 22.04 forces the Firefox Snap default for everyone, across every flavour. Sadly the Snap version of Firefox in Ubuntu 22.04 won’t (currently) let you install GNOME extensions from the GNOME extension website.

Until this is fixed, you will need to install Gnome Shell extensions manually as in this answer by vanadium, but you have also an alternative: the Extension Manager app has been made available in jammy universe repo . It is a native tool for browsing, installing, and managing GNOME Shell Extensions written with GTK 4 and libadwaita.

Till now, it was available only as a flatpak app, but now has been packaged as deb and available in Ubuntu universe repo.

The tool supports (copy paste from the GitHub page):

• Browsing and searching extensions from extensions.gnome.org


• Installation and Removal


• Enabling and Disabling


• Updating in-app


• Screenshots & Images


• Ratings & Comments


• Translations

You can install it running in a terminal sudo apt install gnome-shell-extension-manager or following the instructions in the GitHub page