As of April 25, 2023, reading files in Dropbox has not been working properly. For the time being, we recommend using a browser instead of an app like RaiDrive.
This issue seems to be caused by an unusual(or suddenly changed by Dropbox) response header. The Dropbox API response with an application/grpc instread of application/octet-stream when RaiDrive request a specific Range.
Unfortunately, it looks like we’ll have to wait for Dropbox to take action.