Bizarre Vanishing Beam From Lighting Angle.

I was trying to validate a 2020-P 5c line-in-the-door DDR, when this unusual thing happened. I angled the nickel relative to the main light, and poof, the entire right beam on the triangle just disappeared. It must be very shallowly struck, and when aligned parallel to the light, just vanishes. When turned 90 degrees, there it is again, solid-looking just like all the other devices. It's really odd to observe, and it doesn't happen to any other feature on the coin. You can tell it's the same nickel by the nicks and scratches on the columns.