Info Request: How are published reports hosted (one server, server cluster, round robin, etc?)

When we publish a report to the service... what happens exactly?

Is there one and only one PowerBI server that all my reports are hosted by in the cloud?

Are there a cluster of servers and they take turns serving the reports based off traffic demands?

I know that they seem to be published to servers in my "region" as I can look and see what region I am in and it will say:

Cluster URI ...wabi-us-north-central... in my case (I assume each region has its own).

However, what happens after that?

Is there a delay while it replicates the report pbix to other servers in the cluster?

Does it work like SSRS where each application server (rendering box) connects to a shared database and the database itself holds the report files?  Then when a request comes in the user is connected to whatever rendering server is available and it retrieves the pbix file?

Do the servers cache the files, if you publish an update to a file...how quickly does that make it out into the wild?  Is it possible for users to be connecting to different PBI service servers and the report to get out of sync for a while?

Just want to better understand the details of what happens after we click "publish" in Desktop.

Thanks!