If you’re borrowing more than 80% of the property price, your lender may require you to take out mortgage insurance which covers the lender if you are forced to later sell the property at a loss and are unable to repay your loan. Your lender gets their money rom the insurer, and the insurer then chases you to recover the debt.
This insurance does not protect a buyer in any way, but can be demanded by a lender as a condition of the loan.