Have you double checked the settings for lane keep assist on your Audi? I have a 2018 Q5, and you have the options between "early" correction and "late" correct

Have you double checked the settings for lane keep assist on your Audi? I have a 2018 Q5, and you have the options between "early" correction and "late" correction. If it's set on "late" correction, then it seems to bounce between lanes as your described. When it's set to "early" correction, it indefinitely stays centered (assuming it can see the lanes).