You have installed the DLP Endpoint agent for Mac, but no extension can be seen in the FireFox browser 'Manage your extensions' page
The agent was uninstalled and reinstalled.
Release : 15.5, Mac OS 10.15.x Firefox 74+
The workaround below is effective for individual machines:
To create an MDM profile for large-scale deployments see: how-to-enable-mdm-profile-for-firefox-pl