As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SMOKE TOILET MESSAGE ON TAKEOFF. INVESTIGATED DETERMINE TO BE RESIDUAL DE-ICE FLUID IN ACS SYSTEM. MAINTENANCE COMPLIED WITH PROJECT AUTHORIZATION PA 21-009 BLOCKING OFF LAVATORY VENT TO PREVENT REPEATS DUE TO DE-ICE FLUID INGESTION CAUSING VAPORS IN LAVATORY AREA.