I had similar warning messages with my 21MY 35TDi at the same time I had an engine which was only just starting up from cold. Suspecting the battery, it went into Audi.
We`ve charged the battery but there`s nothing wrong they said.
Ok until a few weeks later and the issue returned. I bought myself a smart charger and charged it up only to find the old problem came back. Attaching a volt meter to the battery I had 11 v, trying to start the car, it dropped to 5v and was flat. A visit from the AA deduced the battery had had it but he arranged for VW Technical to come and do some Audi approved testing. He came the next day, did his bit with his laptop and said I`d love to fit a new battery but if Audi reject the warranty claim, that`s a £250 loss against my name. Fair enough I said.
A jump start and off we went to Audi for a second time. Four days later they were still doing some tests to determine if the battery was at fault. Two more days of deliberation and they still weren`t sure. Until finally... we`ve replaced the battery.