Azure DevOps hosted git, and Bastion, failing to negotiate encryption?

[Nico Kadel-Garcia]

I'm dealing with Azure DevOps git services with which recent, security
hardened SSH clients on a RHEL 8 variant cannot stablish public-key
based  SSH links to the Azure Devops. Other RHEL 8 based systems work
well.

Conversely, Azure Bastion cannot use Azure key vault stored private
SSH keys to access the same RHEL 8 based servers, though they can
reach other hosts with the same private key and the same public key.
I've also used the private SSH key, locally, to connect to the various
servers.

Has anyone else seen this issue? Have there been incremental updates
in RHEL 8 published OpenSSH, or does someone else here have a handle
on public key incompatibilities with Microsoft's hosted services. I've
gotten past the "key vault stored keys must be large enough, and in
PEM format, and can't be cut & pasted into the Azure Portal" issues.