Is a microwave oven a Faraday cage?

Yes, a microwave oven acts as a Faraday cage.

By reflecting microwave radiation inward, the metal enclosure (including the mesh on the door) stops it from escaping. By containing electromagnetic waves, this shields people from radiation exposure while enabling safe food homecareappliances.co.in/bosch-microwave-oven-repair-in-ghaziabad/