In an actual game you are right it could be a silent snap or it could signal a audible or change play check. When we coach this it’s usually to throw the defense off initially because the closer to the center the qb is can signal a rpo or quick hitting play when we check out of it by lifting the leg up and step back it usually indicates a longer developing play so the qb has more time to throw. He can also do the same thing by clapping then audibiling to the next check and stepping back. A goood indicator is if the qb steps back and the wrs Also.
change positions and reset. The chiefs do a lot of that Mahomes is great at changing plays at the line of scrimmage