I was taking some screenshots to use as backgrounds for my computer with my HUD turned off, and when I finished, I noticed this bug that seems to apply whenever you draw back a bow with Oathkeeper equipped. It's kind of funny and makes sense why nobody has noticed this before, because it's perfectly hidden underneath the HUD at all times, but the HUD is just transparent enough that, once you've noticed it, you can find it very easily if you're looking for it.