Hello.
In settings I entered
"https://ns2r.levonet.sk" as custom DoH resolver
Chromium needs you to add /dns-query, but that doesn't make your URL
work (Linux, chromium 98+99). I can't see why. We have kresd 5.4.4
with doh2 on
https://odvr.nic.cz/dns-query and that seems to work well.
(your cert looks OK)
--Vladimir