Since there is no screenshot or what the name of the Adblocker is no one is going to know what to do. You need to check your Addon manager to find what it is or locate it. https://support.mozilla.org/en-US/kb/find-and-install-add-ons-add-features-to-firefox

Firefox shows a purple shield instead of a gray shield at the left end of the location/address bar in case Enhanced Tracking Protection is blocking content. *click the shield icon for more detail and possibly disable the protection You can check the Web Console for relevant-looking messages about blocked content. *https://support.mozilla.org/en-US/kb/enhanced-tracking-protection-firefox-desktop *https://support.mozilla.org/en-US/kb/smartblock-enhanced-tracking-protection *https://support.mozilla.org/en-US/kb/trackers-and-scripts-firefox-blocks-enhanced-track