A deflated mortgage refers to a home loan in which the lender and borrower agrees to reduce the principle amount owing but increase the interest rate being charged.
Depending on how this is being structured, a borrower might end up paying the same amount as the original loan if the new loan is held to it’s full term.
The main reason why such creativity can be entertained by a lender is that the borrower is an investor who wants to claim deductions from interest expenses.