OpenSSH 6.8p1 migrated to using SHA-256 for key fingerprints back in 2015. The SSH agents plugin is still displaying the fingerprints using the MD5 format:

Do you want to replace the SSH Host Key with fingerprint b5:a8:8d:c1:11:e5:c5:e0:53:62:dd:20:e1:da:85:8f with the SSH Host Key with fingerprint 9c:57:4f:8c:21:a9:58:69:e3:97:ba:f4:53:b4:f5:bf for all future connections to this host?

Would it also possible to get the algorithm included in the display? When I got the message above it was actually due to a change in the preferred host key algorithm. OpenSSH displays the key algorithm as part of its host key prompt.