Student Loan Accounts Updated, Credit Dropped 120 points. What can I Do?

I have two sets of student loans. The smaller set of loans were recently updated on my credit report, moving from Nelnet to the Department of Ed. For some reason this dropped my credit from a nice 760 to 640.

I’ve not been playing them since COVID since they’ve been on a forbearance. I never missed a payment prior to that point. I’m also fully prepared to begin playing again in October when the forbearance ends.

What can I do here? I’m ready to call them and discuss, but I don’t want to go in blind. Is this a case for submitting a Good Will letter? Or do I need to first figure out why this hurt my credit?

Thanks for any help you can give. I’m new to dealing with credit issues so I’ll benefit from any knowledge / advice shared.