Solo was released about five months after TLJ so I can see why there would be a correlation between the divisive TLJ and Solo's underwhelming (thus far) box office. TFA and Rogue One weren't as divisive as TLJ has been among fandom.
I didn't watch Solo and I'm not going to. I can't say that any boycott, real or perceived, 'hurts' Lucasfilm in the long run when you tally up all the box office receipts from their previous Star Wars films, and all the other money they are raking in from merchandise. Even Solo, if it loses money, is a loss they can eat and keep moving. But this isn't completely about money, it's also about perception. Disney's once unassailable stewardship of the Star Wars franchise now has to face negative press in ways that it didn't pre-TLJ and from the period of TLJ to Solo, and the boycott (whether it's large or merely a phantom menace) does play a role in that and in giving Star Wars the first black eye of the Disney era. I would also speculate that it would be some of the disgruntled fans who would have been first out the gate for Solo (a movie seemingly tailor made for fans who felt insulted by some of the Lucasfilm response to TLJ criticism) and would be repeat ticket buyers and also purchase tons of the merchandise, while also spreading the word through social media. So, while Disney isn't hurt overall. I mean Disney weathered Lone Ranger, John Carter, Tomorrowland, Alice in Wonderland, and Mars Needs Moms, Lucasfilm does have a headline generating disappointment on its hands. And I think the suits need to figure out what went wrong with Solo and did the problems extend beyond the film itself.
Disney/Lucasfilm could read Solo's 'failure' as a rare misstep and not alter their plans. Or they could see it as their saga films, which made tons of money, are fine, but the anthology films need rethinking. I hope they see it as TLJ, and perhaps more importantly, their PR response to TLJ antagonized fans they should keep in their corner, and that the backlash/boycott to Solo could've been lessened, if not outright prevented, if one TLJ had been better IMO, but also in how they handled fans' complaints about that film which left some people feeling disrespected, frustrated and angry and widened divides in fandom. Lucasfilm had every right to defend TLJ, but I don't think they went about it the right way, and I feel the Solo box office is partially reflected in that. There could be other factors-Memorial Day isn't that kind to Disney, Solo wasn't a film that people were that hyped to see regardless (The idea of a young Han Solo film doesn't seem to have been that appealing, plus while it's the return of old characters, it not the return of the vets like Harrison Ford and Billy Dee Williams), Infinity War and Deadpool 2 are stiff competition, the troubled production drama gave the film a whiff of disarray (a la Justice League), the advertising wasn't as all out as it has been for the saga films (I can't recall if Rogue One got more marketing, but I think that it did. It certainly seemed to have more toys), and so there's other factors that could be at play here, among the ones listed and others I am unaware of. But I also feel the divided reaction to TLJ also was a factor and it's one that I think Disney should be concerned about addressing because now that Solo 'failed' it could mean the start of a slow bleeding out of the franchise.
It's good that Episode IX is next year. It gives Disney time to repair the breach with disgruntled fans. But it also gives these fans time to miss Star Wars and also for the revolting fans to reassess their own views and actions. They might become more emboldened by their 'success' in boycotting Solo, or they might waver or change their minds and become more supportive of Episode IX if they feel Star Wars as a brand is imperiled by Solo's performance. Disney can take this loss as an opportunity to retool, rebuild, and spin it to have a come from behind story. It already raises the stakes for Episode IX and sets up a nice media story about if Star Wars take a punch and get back up. Disney could also take this time to reconnect, or attempt to, with disgruntled fans and see if they can bring them back inside the tent.
For me, I'm not sure if I will support Episode IX. I haven't enjoyed the new saga films, I was turned off by the petulant reaction from Lucasfilm over TLJ criticism. I liked Rogue One. And from what I've seen of the spoilers for Solo I likely would've considered Solo a decent film and likely would've enjoyed it more than TFA or TLJ, but this time I just won't spend my money on another film from a franchise that I felt was too dismissive of many fans who held disagreeing bones of contention (many that I also held) over the last film, TLJ.