libkcapi got updated to 1.3.1 (https://build.opensuse.org/request/show/910806)
and apparently gnutls picks that up now and enables support for it.
It seems like that depends on AF_ALG sockets though, which are currently not
enabled in kernel-obs-build (missing af_alg module), so various builds (libzip,
libvirt) fail with

libkcapi - Error: AF_ALG: socket syscall failed (errno: -97)

I'm not sure whether just af_alg is enough, it might need some other modules as
well.