For the version 1.20.4 Java Edition, the shield animation is bugged in third person. When held in the players right hand in the F5 view, the shield animation is normal, but when held in the players left hand in the F5 view, the hand can be seen poking out of the shield. Its a small bug, but still an issue. I tested to see if it would happen if I switched my main hand to left, but the shield bug continues to only happen when putting your shield into your lefthand (if the player if a left hand user) or offhand (if the player is a right hand user).