How to remove "WaveShare" DRM add-on from Firefox

I stupidly allowed Firefox to play DRM content, and now I have an add-on named "WaveShare" DRM player permanently embedded in Firefox. I'm not happy to have a google binary blob running in my web browser.

I wish to permanently and veritably remove the add-on.

• I am asking about a Firefox add-on not an extension.
• I know it I can click a button to somehow/possibly "disable" it.

Background:

I'm using Ubuntu 22.04 LTS, with Firefox installed via snap. Allowing DRM playback did not need root permission, so it must be installed somewhere inside my home directory.

Mozilla support supposedly has pages on this:

• https://support.mozilla.org/en-US/kb/disable-or-remove-add-ons
• https://support.mozilla.org/en-US/questions/1140262

But these pages do only specify how to remove an "extension" or "theme", not an "add-on".

Other web pages do specify how to remove an add-on, but these are old, and show add-ons that seem to have a "remove" feature. The remove feature has been removed.

EDIT:

So far I've searched for the module with:

find . -type f  | while read file; do strings "$file" | grep -i waveshare; if [ $? -eq 0 ]; then echo "### $file"; fi; done

A sub-optimal workaround: re-install

Warning: This procedure outlines how to backup Firefox bookmarks and saved-logins. Other settings will be lost.

Export Save Logins to .CSV: https://support.mozilla.org/en-US/kb/export-login-data-firefox

Export Bookmarks to .JSON https://support.mozilla.org/en-US/kb/export-firefox-bookmarks-to-backup-or-transfer

Make a note of plugins used: NoScript, Ublock Origin, Privacy Badger, Video Download Helper...

Remove Firefox

sudo snap remove --purge firefox

echo "Warning: this next command may remove cinnamon-desktop-environment too, careful"
sudo apt-get remove --purge firefox 

Remove Firefox User-data for the local user

if [ -d “$HOME/snap/firefox” ]; then rm -r “$HOME/snap/firefox”; fi
if [ -d “$HOME/.mozilla” ]; then rm -r “$HOME/.mozilla”; fi

Re-install Firefox

sudo apt-get install firefox

Re-configure, Re-install add-extensions.

Re-starting firefox shows the DRM add-on is gone.