Sadly I’ve run into the same type of problem with a newer TLD as well. My solution was to get a domain in the older TLD space (e.g. .com, .net, .org). I doubt this will be the last site you run into that doesn’t support a newer TLD and the low likelihood that you’re going to be able to convince someone to fix the issue at every one of those outdated sites means that you’ll eventually need a backup domain for something.
Sadly I’ve run into the same type of problem with a newer TLD as well. My solution was to get a domain in the older TLD space (e.g. .com, .net, .org). I doubt this will be the last site you run into that doesn’t support a newer TLD and the low likelihood that you’re going to be able to convince someone to fix the issue at every one of those outdated sites means that you’ll eventually need a backup domain for something.