Blown shock
 

I recently had my FR-S on jackstands waiting for clutch parts and had to drive the old GTI. I noticed the right rear wheel making a banging noise when I hit bumps. The car's old and I didn't want to deal with it so I just ignored it.
Got the FR-S fixed and started driving it again and it had the same noise as the GTI. WTF? Am I imagining it? Took a look under the car and saw this:

What a coincidence! At least it should be an easy fix.

Apparently both of my rear shocks were leaking @ 37k miles, which is when I found out, so no idea when it started. No banging noises though. Good thing the dealer agreed to replace both. How many miles are on your car?

Bought some almost new 2019 brz dampers, much better damping than the 2013, but after 6 months one of them at the back looks like yours :/

I've got about 200,000 more miles than you. Have you hit anything lately?

Just before the shock started making noise I did something pretty stupid. I needed to jack up the car to replace the underpanels. I thought I would save some time and effort by driving the rear onto ramps and jacking the front. But the jack won't fit under the front with the rear raised. So I spaced some 1" boards so that the front tires would end up on the boards when the rears were on the ramps. BAD IDEA.
First attempt didn't work. I shot the ramps across the street. Reset everything and did it again. When this is happening the car is gently rolling down the ramps, no big deal.
Tried it again. This time instead of shooting the ramps backward, I shot them forward. Under the car. Rear of the car slammed to the ground. Shock blew.

Holy shit. 200k on the same dampers/shocks?! I find most lost their performance around the 60-80k mark. By about 100k when you actually remove them, they barely travel upwards or do anything, even if there's no signs of leakage.

Looks like yours also have the Eibach lowering springs on it too - which actually lower a good bit over stock.

Here's what my ramps look like after the fall. The pinch welds cut through them like butter.

Did you set the e brake on the ramps?

Yeah I have the Eibach Pro-Kit. Made changing the shock a lot easier because the spring doesn't need to be compressed. The job was easy but it could have been easier if I had half a brain and degreased the strut first. But if I had half a brain I wouldn't have blown the shock in the first place.
I just removed the two nuts inside the car, then removed these two bolts and the other one to the left that holds the suspension arm to the car. I also removed the bolt holding the shock to the arm but you don't need to. Then remove the whole assembly.

Your shocks were shot around 150,000 miles ago. Shock degrade is slow and you don’t realize it.

Delete duplicate.