The RSA SHA-1 hash algorithm is being quickly deprecated across operating systems and SSH clients because of various security vulnerabilities, with many of these technologies now outright denying the use of this algorithm. (OpenSSH 8.2)

For example - here is the announcement from OpenSSH regarding their upcoming deprecation of the ssh-rsa algorithm: https://www.openssh.com/txt/release-8.2

When connecting to Git repositories Fisheye allows for ssh key generation : Authentication - either directly or indirectly when connecting Bitbucket Server repositories.

FIsheye generates RSA keys (with sha-1 hash) which can now be rejected: When attempting to use an SSH key generated using the ssh-rsa sha-1 hash algorithm 

the SSH key isn't accepted (the Test Connection for the repository returns a 'Permission denied' message)