So blocks are just happening on public open resolvers and not on the TLD servers? What's stopping people from standing up their own DoH servers? It only takes a few minutes. Install Unbound and see if it was compiled with libnghttp2. If not then it will need to be rebuilt. Politely ask your package maintainer to also build it with libnghttp2.

    unbound -V | grep --color libnghttp2

[1] - https://nlnetlabs.nl/documentation/unbound/unbound.conf/

[2] - https://nochan.net/b/Internet-Crap/20260602-Set-Up-Your-Own-...