In an idiotic move, Mozilla has decided to disable native support for IDN domains.
I personally have been able to get dozens of people to convert to Firefox because it supports IDN domains, by disabling IDN without notice you are not only making my life a living hell (because people will complain and I have to listen), you are also taking away one of the key reasons for people to use Firefox.
Many domain registries and hosting providers even recommend Firefox on their websites because it supports IDN.
I realize it has been disabled for “security reasons“, but I suspect it will take years for domain registries to find a solution to IDN spoofing.
Big mistake Mozilla, this one will come back to haunt you.