I need to clarify: it is working on a macOS using commandline and directly using ssh. When using Secure Shell in Chrome in macOS, it is also not working. Here the corresponding output:
debug1: Next authentication method: publickey
debug1: Offering public key: /.ssh/identity/nameXYZ_id_rsa RSA SHA256:blabla explicit
debug2: we sent a publickey packet, wait for reply
debug1: Authentications that can continue: publickey,keyboard-interactive
debug2: we did not send a packet, disable method