3rd brake light rattle?
 

I have a rattle from the rear deck. I did the fix where you bend that tab over and it sort of fixed it. But today it was doing it again. I pushed the 3rd brake light down. That fixed it completely. Anyone else had a 3rd brake light rattling off the rear window?

Are you sure, it's light, that rattles? It's not that far from other very common and one of biggest common sources of rattle in twins - U latches for rear seat folding mechanism.

Get padded tape and stick it to the side edges of the brake light (do the bottom side too), make sure not to put any on the top side as you'll see it in your mirror!!

It sure seems like it's the brake light. It was doing it on my lunch, I pushed the 3rd brake light down and that stopped it temporarily. Now a few hours later and it's back

One thing to check; make sure the little glow in the dark safety pull in the trunk is securely fastened in its little holder. If it pops loose, it can rattle around a bit.

Can't find it, and it's driving me bat shit crazy... Lol

It's not the 3rd brake light. Is there a fix for the common rattle at the seat latch for the back seat? Or should I go buy high density foam and just pack every hole with foam and cross my fingers

"quick fix" for latches is to tape over them. Unfortunately not long lasting, as few opening/closing of seat back and latching mechanism/teethed gear eats through tape. At least should help to pinpoint rattle source, if those latches are culprit.
Try googling on subaru seat U latch rattle. Or searching in this site. There might be other ways to fix, maybe better. IIRC one of them was to unbolt/adjust a bit latching mechanism position/re-tighten, but don't remember details.

This car has not very expensive high-class interior, rather like in cheap subaru-s. Sound proofing sucks. Audio sucks. Practicality in some ways is limited. Many mention as main drawback stock NA power. Though then again if that all has been much better out of box, i guess car might be more upmarket & priced accordingly much higher. I wouldn't be able to afford new caiman/beamer M/audi S/AMG mercs if new, but i could afford this. So i'm happy with chosen compromises/some faults, as loads of driving fun i'm getting for the money more then makes up for that.

Did the fix with white lithium grease on the loose weld spot suggested on most of the fixes. Absolutely nothing. Still rattling. I'm thinking about getting a crap ton of foam and just filling the deck.