I’m with RBT. Sway bar bushings can get creaky. Shoot them with a shot of Fluid Film where the sway bar enters the bushings. Both sides of the car and both sides of the bushing. If it’s goes away or quiets down, you have your confirmation.That could either be the shocks or the sway bar bushings. I have no idea if that car even has a rear sway bar, but when I have had weird suspension creaks in the rear, that has been the cause in my experience.
My Jeep has a rear shock that looked like yours. I cleaned it up and haven’t seen weeping since. I did get a free set of shocks ( and Rubicon springs) from a friend who put a lift on his Jeep, so I could change it if needed, but it’s not leaking anymore.