Sadly I have to partially agree here.
The movie completely forgets about its main protagonist in the climax. But in a way, it was to make room for Luke and Kylo to finish their arcs, who are both strongly related to Rey in terms of character development.
Watch the “Lessons from a Screenplay” video on hollywood structure – basically, The Last Jedi is a 4-Act movie in a world where 98% of blockbusters are 3-Act or 5-Act movies (3-act and 5-act is essentially the same thing). That’s why it feels weird. Rey’s arc happens in the 1st 3 acts of the movie, while the 4 act is there to conclude the other characters’ arcs.
Rey is a bit like a spectator in this story, but she still has an arc, and they have interesting places to go forward with her story in IX, which is what matters.
In fact, if Rey’s so unimportant… why does everyone agree on here that her scenes with Kylo are the heart of the movie and need to stay in? She’s vital to the story.