@jwh20 feel free to add that as an answer, rather than a comment. I thought that CV joints were designed that the tripod ends could slide in and out of their cups to allow for a change in length, but maybe this is also needed.

Yeah, quite possibly. I can't imagine manufacturers would put a joint into the driveshaft, so maybe it's some sort of weight to counter vibration?

Mine is from a 2016 Mitsubishi Outlander PHEV (rear driveshafts).

The one I have is from a Mitsubishi Outlander PHEV (UK Model). The above photo is just an example image.