If a bank loses/steals your money, what exactly happens? How long until you get your money back?

My savings is currently with Synchrony, and I’m thinking of moving to Brio for their 5% interest rate, but their reviews are horrible. Then I noticed the reviews for ALL banks seem to be horrible — Brio, Synchrony, and Chase all get a 1/5 from BBB reviews, with loads of people talking about how the bank locked their account, lost their money, etc, and they have been fighting for weeks/months to get their money back.

So I’m wondering: if a bank did try to scam you, what would the process look like of getting your money back? You just report it to the CFPB, then they fight with the bank on your behalf? And in the meantime you have no access to those funds? Assuming you did nothing illegal, do you have a 100% chance of getting those funds back? (up to the $250k FDIC insured limit)