I'm unable to search by tag in either the browser extension (Firefox) or on the website.
From looking it seems like there should be something like an "expand search across all fields" option, but I can't find it in the settings.
It looks like v1.16.0 of the extension should allow this, but that version does not seem to be available to install
1Password Version: Not Provided
Extension Version: 1.15.7
OS Version: Not Provided
Sync Type: Not Provided
Referrer: forum-search:tag search