Animation shimmering

nimonsi

Good afternoon. Could you tell me how to get rid of shimmering in hair and sometimes on clothes when I render an animation? If the face is static, everything is fine, but when facial expressions are added, the hair immediately starts to shimmer during the facial animation.

P.S. There is a small workaround: I render the animation at 30fps 1080p, but if I render in 4K, the shimmering effect is much smaller, although it doesn't disappear. Unfortunately, this takes much longer. Is there another way to get rid of the shimmering? Thank you!