I have three sync modules Joel, so I will do a test with mine. The OP has two, he mentioned it, which is why I said it would double his used capacity if he deleted one.
I added mine not for space, but for coverage, in conjunction with repeaters, but I had the added benefit of more cloud space, which I don’t need. I got them in hard to beat deals where they came with a camera included, at 40% off. At the time, they were much cheaper than just an add on camera, which is why I got them.
Right now it’s difficult, because I manage my clips like you, if I recall correctly, by regularly reviewing and deleting, and saving anything of interest, before then deleting the clip in the app. This leaves me running at only 1 or 2% all the time. They must love people like me, because together, such people, will save them an awful lot of cloud space. I wouldn’t be surprised if they could run at a third or less of the space technically sold.
Anyway, I’ll let them build up for a while, and then I’ll delete a third of my storage, before adding it back in, just to confirm.
EDIT: Just checked, and I have four, lol, so I will get a smaller proportional change, but it should still be obvious, if I let it build up enough over the next few days. Don’t think I can be bothered deleting two, for a more obvious change, but I may.