It says, it is to be turned off during the procession, before the Exsultet. It’s then silent about the lights after that.
Then it would’ve said “candles” instead of “lights… throughout the church.” Actually, it would’ve said nothing since #16 already said, “All light their candles.”
It’s not a rubric about electronic lights. It’s a rubric about lights, period. Whatever you light your church with at night is off until the Exsultet when it’s turned on.
That doesn’t make sense only because it’s during the day. The Easter vigil takes place after dark.
The rubric makes more sense in context. The Service of Light starts in the darkness. The Paschal candle is lit followed by “The light of Christ.” Then individual candles are lit followed by “The light of Christ.” That is, those in attendance receive the light of Christ. Finally, all the lights are lit, followed by the final “The light of Christ,” through which the world is lit. The Exsultet which follows is about the light expelling the darkness.
One can argue that keeping the lights off makes the Paschal candle that much more prominent. I can see that. And certainly waiting until the Gloria makes it much more dramatic. But for better or worse, the rubrics are clear that the lights go on before the Exsultet.