That is an excellent question, there should be plenty of records, - especially given the OP's comment "MM savings accounts supposedly opened in 2021 which I never opened and know nothing about."
There would have needed to be a transfer into the MM in 2021 to open it as well - you can't open a MM without money. Its not a savings account, its a security. Also , given MM accounts were paying 0.08% - literally - in most of 2021 - absolutely no one opened a money market account through a bank at that time.
@Cujet, if you are in a position to tell us what happened with this bank we are curious. I realize it might be something you don't want to discuss further, if so that is ok.