12v Battery Replacement

Our 2022 etron has around 40k miles at this point. At 3-4 years old, I'm getting a bit nervous about the 12v battery. Anyone I'd love to get a sense of how long people have been seeing from the factory 12v battery before failure.

I've had a number of 12v failures on hybrids in the last 15 years or so, and the failure modes are - interesting. But at least I could change those myself. My understanding is that changing the 12v on an etron is a dealer service issue - not a DIY project.