For what's its worth I had same car, same year, same issue. Kept topping up and car was fine in sense it drove perfectly . All i needed to do was top up regularly. Until one Sunday driving to the Peak District and it literally went bang without any warning and into limp mode. Long story short needed a complete engine rebuild. Didn't want to pay Audi prices (more than value of car at the time) and absolutely loved the car so tried all sorts with supposed Audi "experts" who often made matters worse. Learnt a lot from this experience so not all bad.
In end i traded it in for a newish car at main dealers, with the half sorted problems, so got a little bit for it but nothing like i would have if if it was a fully working car. I know car prices have shot up so maybe worth being pre-emptive and getting the issue fixed as it maybe worth it, because as i found out once it goes bang, there is a lot of collateral damage too. Repairing that will cost a lot more.
But this was a few years ago and once I'd gotten over the mental trauma of the long and painful experience, ended up buying an Audi again but this time i bought a diesel and kept it cheap(ish) just in case. But got to say (touch wood) the TDI has been exceptional. It was only meant to a stop gap car, but hanging on to it for as long as i can!