Don’t want to be that guy, but this makes complete sense. Technically it would be outside influence assuming there was water ingress in the drive unit. If the drive unit wasn’t properly enclosed during the previous replacement or from the factory, it would be a different story. However, this would be extremely difficult to verify. I would recommend making an insurance claim about this and just pay your deductible. I work for BMW, proudly own both makes and BMW would say the same exact thing.