If they violate the Fair Credit Reporting Act, you can go after them.
A new lender will NOT contact your landlord in 7 years!!
They sound like an ignorant landlord and need to be called on their nonsense.
Within 21 days of you vacating, they MUST provide receipts for work done to you and can deduct them from your deposit. If it’s unreasonable you have to sue them in small claims court to get money back.
If they do not provide receipts to you within 21 days, you are entitled to receive your entire deposit back. DO NOT TELL THEM THIS, it’s not your obligation.
they CANNOT legally charge you for vacant days after you move out, that’s insane and their threat tells me that they are ignorant.
It’s up to you to decide what you want to do. You will have to get a judge to tell them the law.
They cannot make up their own rules!