Expected download rates - OneDrive slow in Azure - Can I improve bandwidth?

I am doing a complex file migration project using both Google Drive and One Drive.

I am seeing really poor download performance figures for OnDrive.

I have a Windows 10 1903 VM in the Azure West Coast datacentre on a D4 instance.

I have about 500Gb of file I need to download from Google Drive and OneDrive.

With Google Drive I am seeing download bandwidths in the order of 400-600Mbps. Huge!

With OneDrive I am seeing rates of 8-20Mbps.  (I have ensured the Sync client has no bandwidth limits)

I specifically spun up the VM inside Azure assuming that the bandwidth would be amazing between my VM and the OneDrive infrastructure.

To my surprise OneDrive is bad, and Google is great.

I am trying to reach out to Microsoft and understand what achievable download bandwidths I should expect (is there throttling from the OneDrive servers), and how can I design my systems to maximize download / upload performance.