Even if you think TLJ was a good movie on it's own I think we can agree after this opening that it didn't set up a good hook for audiences to be excited for episode 9 which is definitely a factor for ROS underperforming, along with the reviews
Nah, the bad trailers/premise for TRoS didn't hook me.
Me after TLJ " Wow, all the legacy characters are gone and a great actor like Adam Driver can be the unhinged heavy for the next movie. Where will they go next?"
Me after TRoS name reveal/premise/trailer " Oh, so killing Snoke was just a lateral move and this series has to have an old wrinkly dude as the big bad for some reason."
Imo, while the people who didn't like the way TLJ ended contributed to the lower boxoffice this is similar to Solo where general audiences didn't care about JJ's trump card of bringing back Palpy.