The TLD registries are supposed to each have defined rules for IDN which can prohibit abuses and to police the use of your service. If you operate the registry

The TLD registries are supposed to each have defined rules for IDN which can prohibit abuses and to police the use of your service. If you operate the registry for say, Switzerland, it makes sense to allow what Swiss and maybe German people would want, then forbid everything else. But if you operate .COM or .INFO or .FREE-MONEY or whatever, your goal isn't to help anybody it's to obtain the most money possible without anybody senior going to jail. Crooks want to pay you money to help them target victims? Yes please. So in practice the browser vendors have to cook up heuristics to try to guess whether the IDN is a trick and in this case I'd guess Chrome's heuristic didn't consider this a problem whereas Mozilla's did. I believe Mozilla were so exasperated by the IDN abuses at these registries they may have just switched off IDN rendering for the entire registries affected which is thorough.