That domain is blocked by Firefox Enhanced Tracking Protection. You can check for issues with Enhanced Tracking Protection. 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 like blocked content. *https://support.mozilla.org/en-US/kb/enhanced-tracking-protection-firefox-desktop *https://support.mozilla.org/en-US/kb/total-cookie-protection-and-website-breakage-faq *https://support.mozilla.org/en-US/kb/trackers-and-scripts-firefox-blocks-enhanced-track

Try to changek DNS over HTTPS to "Max Protection". *https://support.mozilla.org/en-US/kb/firefox-dns-over-https *https://support.mozilla.org/en-US/kb/dns-over-https-doh-faqs