Hopefully, someone had the foresight to have Star Wars: Resistance help fill some of those gaps!
Star Wars: Resistance could show how things have changed since the Resistance’s escape, and how successfully the First Order is operating under the guidance of Kylo Ren.
At least, I’m assuming that’s who’s running the show in lieu of Supreme Leader Snoke, who seemingly died in The Last Jedi.
The point is that some big things happened in very quick succession at the end of The Last Jedi, and The Rise of Skywalker may not have the time to outline all the important things that have made life easier or harder in the galaxy.