The low upload speed to Onedrive has already been reported several times, even with its own API keys.
Among other things, we have a dedicated server at Hetzner with GBit upload, even there we do not get over 400 MBit in the upload, and that only fluctuates very much downwards. We didn't get any higher with OVM servers either (by the way, we achieved the best results when only the chunk size 250M was set as an option for rclone).
Is there anyone who somehow got higher upload rates at Onedrive?
With the chunk size we have actually tried everything from 1-250MB, but thanks.
Since we have such speed problems neither with Google drive nor Google cloud storage nor Azure (there we have GBit without tweaking) nor Backblaze (there we also have GBit upload, but only with: --transfers 5 --b2-chunk-size 600M - -b2-upload-cutoff 600M), it will probably be due to Ondedrive.
It's actually a shame that MS obviously wants to urge its business customers to handle everything via Azure.
Are you using IPv4 or IPv6? I've seen IPv6 is sometimes way slower. I force my connection to use IPv4 and get very good speeds (max my gbit upload) with the default 4 transfers and a chunk size of 160M.