New pads squeal more than the old ones

Ask what changed right before it started. If a shop can't duplicate it on the 2021 Audi A6, bring a video plus freeze-frame data, not just a story. Save the big job until that test fails. Write the result down so the next test isn't a repeat of the last one. If it repeats twice more I'll book time.

Intermittent stuff lies if you only catch it once. A pressure test beats staring at a dry driveway if the 2021 Audi A6 is losing coolant with no puddle. That's the branch I'd chase this week. On “new pads squeal more than the old,” that was the fork that mattered for me. Write the result down so the next test isn't a repeat of the last one. Next check is the cheap one I can do in a driveway.

I wouldn't throw parts yet. Capture voltage while the 2021 Audi A6 is actually failing — after it restarts you've lost the clue. You'll know quickly if you're on the wrong tree. Time, temperature, and whether it's in gear are the notes that actually help a shop. If that fails I'll eat the diagnostic fee.