half time adjustments (what are they, and are they legal in the SEC)

Watching games today and a lot of teams are doing these tricky things called “halftime adjustment” apparently this is a sneaky trick where you change up all your plays, formations etc. Apparently, you can even change out QBs to confuse the other teams defenses.

Is this allowed in the SEC? Do you have to give up some recruits or pay a big fine or something? I am not saying that we should absolutely do this at LSU, but maybe it’s something we should look at with new coaching staff