%-wise it's a similar drop to the second installment of the last two trilogies. So I understand framing it that way. And to some extent I agree.
That said, I feel like we have to address that the modern blockbuster world is very different from even 15-20 years ago. Sequels in long-running, healthy franchises do not usually drop that much in the 2010s. Like, you can say TFA had the novelty factor/nostalgia to buoy it, but, just to pull an example out of my ass, Furious 7 to F8 had a much healthier drop despite not having the novelty of the Paul Walker situation. The interest was there for the opening for TLJ. Even considering the Christmas holiday on the second weekend, December blockbusters just normally don't drop out like that. A sequel drop that severe in this movie age is very abnormal.
IMO, I would say the WOM for TLJ was not bad, just sort of iffy, like, audiences liked it well enough, but they weren't excited about it like they were with TFA, bringing their friends and family to see it again and again.
I say this as a TLJ fan. However, I feel like TROS still gets the majority of the blame. This implosion on the weekend along with the Cinemascore doesn't tell me that this is being buried under people not liking TLJ. It is audiences more or less shrugging their shoulders. I can't say what the final legs will be, but I feel pretty confident that if TROS underperforms, it'll be mostly because audiences rejected it and not because of a hangup for TLJ (even if that factors into it somewhat).