I love this addon. Recently google change reverse image search with lens. This addon has an option internal page in contextual menu in 3 dots right side of name in Firefox Addons (about:addons)
Select google and update with this config:
Search URL:
https://lens.google.com/uploadbyurl
Search Variables (One per Line):
url=::$URL::
Finally click in Update Options button.
and now is fixed.