@Rosalilia0 Airbnb handles cancellations and refunds according to the host's cancellation policy that was in place when you booked ( anything hosts change on their listings only applies to bookings made after those changes) Which in this case, according to what you wrote here, would be the "Moderate" policy. If you really cancelled this reservation 6 days before check-in, you indeed should have received 50% of the total room cost, plus the cleaning fee, back.
This has nothing to do with the host perpetrating some fraud, if there is an error in the refund, that's Airbnb's doing and you need to pursue this with them, not the host.
They do make errors- once one of my guests was charged double my room rate and both she and I saw the error right after she booked. Airbnb did refund her the overcharge.
If you happened to use the "pay less upfront" option when you booked, then you wouldn't be due any refund, because the 50% is based on the total cost of the booking, not on what you paid upfront.
I wouldn't jump to conclusions that you've been somehow defrauded without contacting Airbnb to find out why the refund appears to be incorrect.