The answer to 'why is my GFCI outlet power surge' is that a GFCI (ground fault circuit interrupter) outlet can trip or surge due to several common issues. GFCI outlets are designed to quickly shut off power when they detect a ground fault, which can happen if there is a problem with the wiring, a faulty appliance or device plugged into the outlet, or moisture getting into the outlet.
Some common causes of GFCI power surges include a short circuit, a ground fault, a wiring issue, or a problem with the GFCI outlet itself. Symptoms may include the GFCI tripping frequently, the outlet not working, or power flickering. Solutions can range from resetting the GFCI, fixing a wiring problem, or replacing the GFCI outlet if it's faulty. For any complex electrical issues, it's best to call a licensed electrician to diagnose and repair the problem safely.