Uppy companion - upload protocol configuration


I’m using Uppy companion and setting the protocol in the options object according to the documentation.
However, I see that no matter what I set the value to be (‘tus’ for example), the actual protocol used is ‘s3-multipart’!
Looking into the source code, I noticed that in “@uppy/companion/src/server/Uploader.js”, in the “reqToOptions” function, the protocol being used is taken from “req.body.protocol”, and not “req.companion.options.protocol”!

Any idea why is that?
Where’s the “req.body.protocol” coming from?
How can I change it?