Is the Ad Blocker you want to turn off running as a Firefox Extension? If so, click the hamburger menu in the upper right corner of the browser, then select 'Add-ons and themes' from the drop-down menu. This opens a window where you can manage your extensions, like Ad Blockers. Toggle the extension off (blue on/gray off). Or, to remove the extension, click the three-dot button to the right of the extension on/off toggle button and select 'Remove' to trash the Ad Blocker completely.

The site may be having an issue with your Enhanced Tracking Protection settings.

https://support.mozilla.org/en-US/kb/enhanced-tracking-protection-firefox-desktop

Hello

Other disable ad blockers messages? https://support.mozilla.org/en-US/questions/1449425#question-reply https://connect.mozilla.org/t5/discussions/disable-ad-blockers-messages/m-p/58263