Me thinks it is most likely either the relay that controls the dimming bright and dim during start up, or, as you say the wiring. It started after a couple good snowfalls here in N. Central IL and so much salt being used on the roads. But here's the thing: Upon start-up in the dark garage, that driver side LED is dimmer than the passenger one. Then, when the car gets out into the daylight, it lightens up evenly. So it could also somehow be the light sensor? I've tried covering the dash-mounted light sensor to fool it into thinking it's dark. The only thing that changes is the instrument panel brightness so that seems to be working.