Once a capsule that requires a client certificate has been visited, every subsequent attempt to access another capsule without client certificates fails with an SSL error 26.
After gmnlm has been restarted capsule access is fine again.
could be closed, fixed in https://git.sr.ht/~sircmpwn/gmni/commit/fcc5c1d374c68807a535018c2fc70c48d576f6bf