On the https://man.sr.ht/wiki/create/ref page, in the "Or choose an existing ref" sexion the links end in /refs/heads/branch, which 404s: https://git.sr.ht/~nabijaczleweli/klapki/refs/heads/trunk.
/refs/heads/branch
/log/branch or /tree/branch might be better.
/log/branch
/tree/branch