Although not 100% of the destination types support throttling, OneDrive v2 does if that’s what’s in use.
Here’s what happens on mine without throttling (at 11:20) and with --throttle-upload=100KB (at 12:20):
2020-04-27 11:20:34 -04 - [Profiling-Duplicati.Library.Main.Operation.Backup.BackendUploader-UploadSpeed]: Uploaded 45.25 KB in 00:00:00.8894220, 50.87 KB/s
2020-04-27 11:21:23 -04 - [Profiling-Duplicati.Library.Main.Operation.Backup.BackendUploader-UploadSpeed]: Uploaded 23.63 MB in 00:00:50.1186602, 482.89 KB/s
2020-04-27 11:21:26 -04 - [Profiling-Duplicati.Library.Main.Operation.Backup.BackendUploader-UploadSpeed]: Uploaded 35.20 KB in 00:00:03.3229027, 10.59 KB/s
2020-04-27 12:20:40 -04 - [Profiling-Duplicati.Library.Main.Operation.Backup.BackendUploader-UploadSpeed]: Uploaded 45.29 KB in 00:00:01.8628526, 24.31 KB/s
2020-04-27 12:28:02 -04 - [Profiling-Duplicati.Library.Main.Operation.Backup.BackendUploader-UploadSpeed]: Uploaded 35.96 MB in 00:07:24.5803222, 82.83 KB/s
2020-04-27 12:28:04 -04 - [Profiling-Duplicati.Library.Main.Operation.Backup.BackendUploader-UploadSpeed]: Uploaded 41.14 KB in 00:00:01.9487112, 21.11 KB/s
Duplicati 2.0.5.1 by default has added a concurrent upload capability in order to increase the speed.
I’m guessing that’s why my 100 KByte/s setting doesn’t quite get hit, or it might be something else…
--asynchronous-concurrent-upload-limit (Integer): The number of concurrent
uploads allowed
When performing asynchronous uploads, the maximum number of concurrent
uploads allowed. Set to zero to disable the limit.
* default value: 4
A similar test to Google Drive with that dialed back to 1 concurrent was just about at target 100KB/s:
2020-04-27 10:48:01 -04 - [Profiling-Duplicati.Library.Main.Operation.Backup.BackendUploader-UploadSpeed]: Uploaded 42.47 MB in 00:07:22.9627872, 98.17 KB/s