Apparently there was a brief glitch with the App Store. The notifications are correct, and as indicated above, you could "Update" by going to the "Purchased" link in the App Store (signing in may be required).

From what I have read elsewhere and my own experience, the problem has been resolved and updating in the usual manner is once again possible.

On a Mac since 1984.
Currently: 24" M1 iMac, M2 Pro Mac mini with 27" BenQ monitor, M2 Macbook Air, MacOS 14.x; iPhones, iPods (yes, still) and iPads.