I tested it now and it was working to some extend (although Google result is not as good as it used to be). If there are issues, please post it to support for proper investigation.

Google has removed their reverse image search and changed to lens which is not like before.

It only accesses 'google.*' sites.

Originally it only had a permission for 'google.com' but then it failed on 'google.co,jp'

https://discourse.mozilla.org/t/support-igoogle/12480/19

It is not practical to list all google TLDs like 'google.com, google.co.uk, google.co.jp,' etc

The permission API at the moment doesn't have a system to include a wildcard in TLD and that is the reason a general all sites permission had to be used. I had asked (11 months ago) for a better API but it was not accepted.

https://bugzilla.mozilla.org/show_bug.cgi?id=1362849