The validity period of one of your driving licence classes has expired. What are the consequences of this?

If the validity period of a driving licence class has expired, you are no longer allowed to use that class. This means you lose the right to drive vehicles in that category, and it becomes illegal to operate them until the licence is renewed. Both that the driving licence ends for this class and that it is prohibited to drive such vehicles are correct. There is no exception allowing private use with an expired licence. Always make sure your licence is valid for every class you want to drive to avoid fines and legal issues.