I found this thread, "I cannot open the Duolingo website from my Firefox browser on MAC", here in this forum, which describes the same problemI'm having. That thread was posted about a year ago and is now archived. For me, the problem is not with MAC but with Windows. I can reach the login page for duolingo.com using either Firefox or Edge, but after giving my log-in information, the website gets into an endless loading loop when I try to use Firefox. It still loads correctly in Edge and I can use that. I've been using Duolingo in FF 102.7.0 esr (32-bit) (and all previous esr versions) with no problem until today and I've been using it for years. I clear the cache every time I close the browser. I cleared it multiple times and rebooted the computer. I tried disabling the ad-blockeer which has never been a problem before. None of these things helped. Thanks for any thoughts on this.