The deposit is a sum with a specific purpose, paid before or during the contracting process, and it doesn't automatically become part of the sale price.
Ask the bank in writing: When is it refundable?
When can it be deducted?
And does it become part of the down payment if the Murabaha transaction is completed?
The most important point is not to pay any amount before understanding its purpose and what will happen to it if the deal falls through.