Weird policy violation warning

Hi Everyone – I’ve been selling an Amazon for over a decade, and this morning I received a policy violation warning that I’ve never seen before, nor do I understand what it even means. I’ve changed nothing about how I package and ship orders. Can anyone help me understand what this means? Below is the warning:

Hello,

We have found that you have violated a policy. If this issue continues, we may deactivate your seller-fulfilled offers.

Why did I receive this message?

We have observed that shipments for some of your recent orders have been confirmed prior to handing them off to a carrier. Sellers on Amazon are not allowed to confirm a shipment before they have sent at least part of the order to the buyer.

Aren’t all orders “confirmed” before the carrier picks them up? I prepare, package, and print shipping labels for all my orders the night before. The next day the carrier picks them up off my front porch. It’s the way I’ve always processed shipments.