I have the same on a Q3 sportback 2024.
Audi have had it 3 times and have now told me that’s what it’s supposed to sound like. I said what Audi have purposely added a really annoying noise on an expensive car as standard. They did change the activated charcoal line in mine as that is a common issue as they split but it has made no difference. I have had other mechanics say it could be transmission, turbo, air intake timing belt/chain or electrical.
I said to Audi what I don’t want is to come back when it’s out of warranty and then be told I have a big problem and it’s going to cost me a fortune.
The thing is quite a few people have the same issue so there has to be a problem.
