Loose sound deadening material inside the front driveshaft

Just pulled both of the driveshafts from 2010 Toyota 4Runner for complete overhaul. After getting ready to pain them and install new u-joints, I noticed that there is something loose inside of the front driveshaft. I talked to driveshaft balancing shop and the guy said that this sounds like something is loose in there. Usually there is cardboard inside.

Here is the video of what it sounds like:

https://youtube.com/shorts/xtcIzM3QoMo?feature=share

Any idea what this may be and if the balance is still okay?

 

What choice do you have, run it or replace it. Or maybe drill a small hole and fill it with spray foam. I'm just guessing...