The answer to 'why is my surge protector tripping breaker' is that the surge protector is likely overloaded or has a faulty component. Surge protectors have internal circuit breakers that will trip if the connected devices draw too much power or if the surge protector is damaged. This is a safety feature to prevent electrical fires.
Common causes include plugging in too many high-power devices, using an undersized surge protector, or the surge protector reaching the end of its lifespan. If the breaker trips frequently, it's best to unplug the surge protector, reset the breaker, and try plugging in fewer devices or using a higher-rated surge protector. If the issue persists, the surge protector may need to be replaced by a professional electrician.