I thought it was because the tail light was bad so I replaced it and the same LED strip was out on the replacement light, which points to something to do with the connection. From what I saw there was just one connector to the light so I'm not sure where the problem could be.
I tested the reverse fog light and the reverse gear lights on the tail light and they worked fine, but after a few weeks the reverse gear light would work sometimes and not others (and later failing altogether and causing a warning on the dash to come up), which again points to something other than the light itself. Anyone have an idea of what I can check/replace to fix it?
The car is a 2015 Audi S3 (8V) sedan. Pictures of the lights below for more reference.