DNS-over-QUIC is a short-lived initiative by AdGuard and NextDNS. It works, but DNS-over-HTTPS/3 is going to be the new popular standard. It is already supported by AdGuard Home (local DNS server/forwarder) via h3 links "h3://22.214.171.124/dns-query".
I don't quite understand why DNS-over-HTTPS/3 is the preferred standard and not DNS-over-QUIC, which has lower overhead and carries less metadata than DNS-over-HTTPS/3. I understood that DNS-over-HTTPS/2 was preferred because it used TCP port 443 and blended in with the rest of HTTPS/2 traffic, making it difficult to block, unlike DNS-over-TLS, which could be easily blocked by blocking TCP port 853.
Just like DNS-over-TLS, DNS-over-QUIC stands out by using UDP port 853, unlike DNS-over-HTTPS/3 that blends in with HTTPS/3 traffic because both DNS-over-HTTPS/3 and HTTPS/3 use UDP port 443, but HTTPS/2 still dominates the web. That means neither DNS-over-HTTPS/3 nor DNS-over-QUIC blend in with most traffic on the web and can be easily blocked by blocking UDP port 443 and UDP port 853. If you consider all that, DNS-over-QUIC makes more sense because of overhead and metadata and yet DNS-over-HTTPS/3 is the one gaining attention and being supposed by all 4 major providers (Google, Cloudflare, AdGuard, NextDNS).
AdGuard developers stated that DNS-over-HTTPS/3 added no value compared to DNS-over-QUIC, but Google has already decided to support DNS-over-HTTPS/3 and not DNS-over-QUIC on Android devices natively (without any apps).