Although I personally wouldn’t deal with BofA because of their size and typically higher rates, I highly doubt they have been approving loans then pulling them a few days before close.

Perhaps they approved a buyer for a certain amount then the other UW factors didn’t pan out to get final loan approval.

Not that its 100%, but if they can’t show you a pre approval from a new lender in the next day or two, then I would give notice to perform and place BOM