As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLIGHT 2200. MASTER WARNING LAV SMOKE WENT OFF DURING CLIMB. PASSENGER CONFIRMED VAPING IN AFT LAV. LIGHT AND MESSAGE WENT AWAY. REMOVED FROM SERVICE. PERFORMED GVI OF AFT LAV SMOKE DETECTOR, NO DEFECTS NOTED. PERFORMED OPS TEST OF LAV SMOKE DETECTORS, REF AMM TASK 26-14-01-700-801-A. OPS TEST GOOD. A/C OK FOR SERVICE.