I think there were multiple factors -- timing, the budget that went over, etc. -- into what happened.
I think Marvel did a better job marketing their stuff. I mean, we knew about Solo's troubled production long before any of the other details.
To be fair, I don't think Solo was a movie that a lot of people wanted and I think the execution was lacking (it really felt like there was a checklist the filmmakers were going through). I don't think we need to invoke TLJ hate to explain why the movie didn't click; I'm sure it was a factor for some people, but, as noted before, there's good reason to believe that they're not the majority.