I’ve seen spetsnaz using M4’s in training.
There’s usually one in a group that is using them running their ops.
The action in Kenosha when Kyle Rittenhouse justifiably and morally killed two Antifa subhumans and severely wounded a third subhuman brilliantly showed the combat effectiveness of the M4 design. It was short and handy enough to allow Kyle to maintain full control of his weapon when one subhuman tried to grab it and after he was knocked down when two others tried to kill him.