Is the down payment agreed upon with the tenant, who canceled the agreement before the beginning of the month, the right of the landlord or the right of the tenant, especially after the leased property has been rented to another person?

If a down payment is made before the contract is concluded, it must be returned to its owner, because the seller is not entitled to it. However, if it is paid after the contract, and custom permits taking a down payment, then there is a difference of opinion regarding the seller's entitlement to it. The more cautious approach is to return it, to avoid disagreement.