The phrase "to lose the deposit" means that you will not get your money back, or you will have to give up a certain amount of money as a penalty or fee. Full definition
They can also tell you how likely you are to not lose the deposit if you do walk away. (money.stackexchange.com)
If they either fail to respond or choose not to respond, that could allow you to withdraw from the deal without losing your deposit. (money.stackexchange.com)
I didn't just lose the deposit for that hotel, I lost the whole fee. (refinery29.com)