openSSH 8.4p1 as installed by Homebrew still references /usr/local/opt/ldns/lib/libldns.3.dylib, which is now incompatible. ssh fails as does all apps relying upon it. The reference should be /usr/local/opt/ldns/lib/libldns.dylib.
You should take this up with Homebrew - we have no control over how they install OpenSSH
closing resolved bugs as of 8.6p1 release