I've actually got a video posting about this exact thing in just a bit. Way to early to write this off as a Star Wars thing.
their crowds in summer have been massively down the last couple of years while up the rest of the year due to their tier pricing, making it really expensive to visit in summer. The last couple of years people have said that summer is now their off season due to it.
The vast majority of their annual passes, outside of the expensive ones, are blocked until the end of August or early September, and a very large portion of Disneyland's attendance is from locals and passholders.
Their advertising has delivered a message very easily misunderstood- that the entire park was going to be massively overwhelmed, overcrowded and that you needed a reservation to get into the parks themselves. I've got several family and friends that were confused by this and that I had to explain that reservations were only for Star Wars, not the rest of the parks. They also didn't believe me that the crowds weren't huge and didn't want to deal with them.
And then yes, they haven't opened up the second main attraction in the land- and just announced again that it is delayed. Though honestly outside of park fans I don't think that most of the general public are aware of or affected by that so much. They just see the land as a whole.
there are a few other things, but really the issue isn't Star Wars, it's that the park leadership, management, and advertising have all combined to reinforce that this summer isn't the time to visit.