Disable Firefox Plugin Check
This article explains how to disable the firefox plugin check
This is how to disable the plugin check in Firefox:

In the address bar write: about:config

At the filter bar search for blocklist and make these changes:

turn “extensions.blocklist.enabled” into false

modify “extensions.blocklist.url” and delete the url

modify “extensions.blocklist.itemURL” and delete the url

modify “extensions.blocklist.detailsURL” and delete the url

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