As far as I understand, Palpatine did not know that with the help of the 1000 Jedi, Rey suddenly mastered this ability. Before that, she was helplessly exposed to the force lightnings. And as far as I know, when a Jedi uses this technique, a Sith Lord can no longer end the force lightnings on his own.
Kardanwelle1994 Yeah but is that point made at all in the movie? If it’s not established in the movie people are just gonna think Palpatine is dumb for continuing to electrocute Rey and let the lightning bounce back at him