“Is the dark side stronger?”
“No! no, no… quicker, easier, more seductive."
With what the movie does, the changes that have been done so far, and things being proposed this is what I’m thinking:
As Jarbear said, we’ve been seeing Rey being drawn to the dark side in TLJ, and you could argue even in TFA. She’s been using it as a shortcut to achieve her goals. Now cut to TRoS, where we finally see her trying to slow down and train as a Jedi, but it’s not working, she calls to the Jedi but no one answers, during the training course we see that her Jedi fighting technques are failing her, we see her get more and more angry, lose control, and take that shortcut again to finally hit the ball. Her use of the dark side here ends up triggering a vision (unlike the theatrical where everything, even Rey getting mad, is implied to be a by-product of her connection to Kylo). So here we see first hand that there is darkness inside her, and we have a vision of her turning dark.
Now on Pasaana, she finds a Sith dagger, and as soon as she picks it up, it calls to her through whispers in her head, she gets a worried look (we cut the mom scream and the line “horrible things have happened with this”). The lightsaber once called to her, and we took it as a sign she was destined to become a Jedi, but we now see the opposite. The lightsaber is now silent and broken because of her choices in TLJ, perhaps she broke her chance to become a Jedi, maybe now her destiny is to become a Sith, just like we saw in the vision.
Then on Kijimi the inscription in the dagger is translated, and it is revealed that the dagger calls out to those with great darkness within them or something like that, something that cements that the reason she heard those whispers is that the dagger sensed her inner darkness. Then she hears those whispers once more on Kylo’s ship, and she ends up following them. When she finds the dagger she again looks worriedly as it starts whispering to her again, only now she understands what that means (so you could even keep her saying “no” as in “no, I’m not evil, stop talking to me”). Then, if that idea pans out, she would have a vision here. You could sprinkle some more evil Rey foreshadowing in it as it’s very relevant.
“If once you start down the dark path, forever will it dominate your destiny, consume you it will”
So now by the time we get to Endor, everything is setup in it’s place for the edit that’s already in V1. Now it’s clear that following those whispers means Rey is descending deeper and deeper into the dark side, culminating in her meeting her “true self” inside the Wayfinder room. Now Kylo’s words ring far more true to the audience: “Look at yourself. You wanted to prove to my mother that you were a Jedi… but you’ve proven something else.”
Rey chooses to literally “follow” the dark path, which consumes her to the point she ends up stabbing Kylo with no hesitation. It truly feels like she can’t escape her destiny of becoming a Sith, so she exiles herself on Ach-to. But now in this version Luke not only gives her a pep-talk, he gives her a new, fully functioning lightsaber, a new chance to fully embrace the Jedi. So now on Exegol the struggle is clear, recover the light or embrace the dark, and notice how she doesn’t use the new saber until she finally chooses to firmly stand against the dark as a Jedi. It’s almost like this is how it was always meant to be.