When prone (single rest) during rain, the dinosaur’s inner‑body surfaces glow brightly

Stegosaurus inner‑body model glows abnormally when doing single‑rest prone animation in rainy weather

During in‑game rainy weather, when my Stegosaurus uses the single‑rest prone animation, the inner surfaces of its model light up abnormally.
This is not a graphics setting issue. I have tested both low and high graphic presets, and the glow still occurs on every setting.
Please see the attached screenshots and video for details.

The Stegosaurus should not produce this extra inner‑body glowing lighting effect when single‑resting in the rain.