Hello!
I am a maintainer of hidns-co and hidns-vip, free subdomain services. We are registered with the PSL(https://publicsuffix.org/list/public_suffix_list.dat) and our users want to connect their hidns-co and hidns-vip domains with Vercel however, when we try to add a hidns-co or hidns-vip subdomain to Vercel, it says that another account is already using the domain, and asks us to create a _vercel.hidns.co or _vercel.hidns.vip TXT record, which is not possible for us as then only one person would be able to do that at a time. We want each user to be able to use Vercel on their subdomain (example-hidns-co / example-hidns-vip). I request you to help us regarding this matter.