Hi,
I had the same issues on my A6 C7.5 and it wouldn’t stop popping up now and then.
These Christmas lights only comes on turning full right and OBD 11 scans shows consistent right wheel speed sensor and open circuit.
Vartar AGM Battery, 2 wheel speed sensor Bosch / Original Vag, wheel hub/ bearings, Audi factory reflash but no avail.
Workshops also run out of ideas. My final guess is the wheel speed harness but we don’t see any bad wiring undercarriage.