When using a custom domain on Firebase App Hosting, we encountered the inconvenience that Punycode is not supported. As a result, we had no choice but to repurchase a new domain and redeploy our site. If Firebase App Hosting were to add Punycode support for custom domains—enabling the use of Hangul-based domains—Korean developers would be much more likely to adopt Firebase services for deploying their sites.

Thank you for taking the time to read my suggestion.