Power distribution block, that’s a lead free soldered pcb, with tin whiskers causing intermittent power loss to subsystems and not triggering a single fault code. Even more fun when it the active sway bar hydraulic system that is fundamental to safe handling mid corner, what bmw calls dynamic drive. Basically a hydraulic pump that sends 2500psi to the sway bars, sway bars are split in half and joined by a hydraulic linkage, up till about 0.5G of lateral acceleration the car stays perfectly level.
Happens once every few months where system turns off randomly for a minute or two, sure makes things exciting.