I updated the NS records at my Hetzner, checked through DNS checker they are propagated. Also dig tool shows they are propagated, but still I have the status “pending”
What feature, service or problem is this related to?
You have added the 2 Cloudflare nameservers as NS records to your DNS. Instead you need to remove the 3 Hetzner nameservers (ns1.your-server.de, ns.second-ns.com, ns3.second-ns.de) and use the 2 allocated Cloudflare one as the authoratitive nameservers.