When Private DNS servers, such as dns.google.com and cloudflare-dns.com, are specified in Android 11+ devices, they are supposed to be converted from DNS-over-TLS to DNS-over-HTTPS connections automatically as per this report - https://twitter.com/MishaalRahman/status/1549488111045967872 . That does not happen on GrapheneOS. I think dns.google.com and cloudflare-dns.com are the only servers that do that participate in such conversions.