What would cause tail light to go out when brakes are applied?

A tail light that goes out when the brakes are applied could be caused by a few issues. One common reason is a short circuit in the wiring, where the brake light circuit interferes with the tail light circuit. Another possibility is a faulty brake light switch, which could create an improper electrical connection. Additionally, a bad ground connection or a burnt-out bulb could also lead to this problem.