Firefrox after new operating system iOS 15.0
Since installing Mac iOS 15.0 on iMac, Firefox does not work.
Wšykne wótegrona (1)
Since you mentioned using 15.0 on a iMac you may have the firewall on OS blocking Firefox. See https://support.mozilla.org/en-US/kb/firefox-blocked-macos-15-sequoia-firewall-what-you
I moved this thread from Firefox for iOS (for iPhone/iPad) to Firefox section as you mentioned iMac which uses macOS. iOS is the mobile OS used on iPhones and early iPads as current iPads uses the similar iPadOS.
Wót James