If it is like with the introduction of the euro in Germany you could still use your old money for a while in shops but they weren't given out or issued anymore. Your change would't be in Mark and Pfennig but Euro and Cent. As they are not issued anymore beyond 2022 the date should be correct as they are issuing dates (as far as I am concerned).
Yes, that's the point: you'll know much better than me how this matter actually works here, but I cannot see anywhere (else) what exactly the periods showed for currencies mean .