Green’s Dictionary of Slang

a slap, a smack, usu. given to a child.

1966		R.H. Rimmer Harrad Experiment 169: My mother wailing; ‘Es passt nit! I told you Saul, Harry’s not to old for a potch.’.
1996		Country Yossi Family Mag. Sept. 🌐 I think these days children speak disrespectfully because they never tasted a potch – which stops chutzpah on the spot – from the start. Parents are afraid to hit and end up arguing with their children and/or criticizing, condemning, blaming, shaming, etc, which causes severe emotional/mental damage to a child (and encourages arguments).