I read the portability clause of your agreement, the window allowed, the minimum amount, then price three scenarios over the same period: porting with a blended rate, breaking and starting over at today’s rate while paying the penalty, or switching lenders. The right choice depends on the rate gap and the time left in the term, not on a principle.
Your current lender wants you to port, and it will not tell you when breaking would cost less. I run the numbers both ways. And if porting is the right choice, I fit the sale and purchase dates inside its window so the penalty does not land by accident.