After configuring the public key according to the official website method, ssh -T git@git.coding.net appears when entering the command

The authenticity of host 'git.coding.net (blahblah)' can't be established.
RSA key fingerprint is 
blahblah.
Are you sure you want to continue connecting (yes/no)? 
Host key verification failed.

Why is this?

My coding project can be pushed and pulled normally, and so can github, and it is normal to use ssh -T on github