Bad earth
The computer isn't telling you the bulb is gone. It's saying "circuit failure"
Electricity finds the easiest path to earth. If the easiest path is through the resistance of another bulb, making that work too then you have a very bad earth circuit
Whilst it's doing it's worst Christmas light impressions, just thump one of the rear clusters and see which one is causing the problems. Then I'd take the rear light cluster out and check resistance of the earth line in the cluster to earth which should be near zero
More often it's a bad contact where the connector makes contact at the rear cluster circuit board or it might be where the earth wire contacts the car body