I'm not certain, but my first glance at this would be that git is not a good candidate to move to a cloud, at least if you want to take all of the advantages of

I'm not certain, but my first glance at this would be that git is not a good candidate to move to a cloud, at least if you want to take all of the advantages of cloud architecture, as it is promoted by the cloud services. You would have to think of some way of federating git repos onto local storage (local to the git process), to avoid network latency inside loops, etc. But maybe that's what Atlassian did and it still didn't work out, or maybe they thought of that but something else (have to fit into the Atlassian cloud architecture?) outweighed it. Point being, you really need to design the cloud architecture around the way your hosted programs were designed to work.