I couldn't find anything online about this issue so I hope this helps someone later on.
My sunroof has been rattling for a while now. You'll hear it every bump and, more annoyingly, rattle along to whatever song is playing. The rattle is likely due to some foam cushioning a bar in the sunroof hardening and breaking off. I just cleaned the area, wiped with IPA, then cut some foam weatherstripping to size and stuck it on. I used 1/2 inch thick foam that I cut down to 1/4 in thick just with some scissors. You can see where the old foam used to be, just put it as it was before.
While I was in there cleaning everything, I also wiped clean and lubricated the tracks and applied some silicone lubricant to the seal on the edges of the glass to keep it pliable. In all, this took about an hour or two.
Besides addressing the sunroof drain issue (either DIY or the new part that just came out), this should be all the maintenance the sunroof needs.

Foam Position:


Everything I Used: