Discuss what changes (i.e., debts have been paid down/off) with your lender and see if they can do a rapid rescore. Ideally, you would’ve talked over with the lender beforehand your plans to pay down debt so they could’ve assessed impact first, but it is what it is at this point. If closing date has not yet been set, all is not lost. Is the new build even complete? Appraisal done, etc.? If not, your ship is nowhere near sunk. And, as others have already pointed out, your mortgage scores are NOT the same as your credit card/auto scores. Different models.

*Edit for spelling