Ah, I hadn't even looked there for mine. Manual says there's 3 settings available (Std, Enhanced, 8k Enhanced) with the Enhanced being the Default setting.
Just checked and mine are all at Enhanced.l
All this said if it's not the cable and you tried a different input, that points to it being something about your Shield.
In any case is it worth a worry over, do you believe the Shield is capable of delivering 4/8k video at rates high enough the setting will make a difference?
Enhanced
Select if your TV, the source device, and
cables support high quality 4K 60Hz
4:4:4 8 bit, 4:2:2 or 4:2:0 10 bit viWell a