Problem is, the writer uses the "official" opening weekend metric, which, for Solo, is May 25-27. I.e., Fri-Sat-Sun. I don't know whether early screenings on Thursday factor into that. But holiday weekends should have that Monday factored in, too, as I saw Solo the second time on Monday, with friends who I could only see it with that day because it was a holiday. So yeah -- over the same three-day stretch, Solo only made $84M to Justice League's $94M, but over its full weekend it made $143M, which is half again as much as Justice League did. The numbers need more caveats, and the general language of the article feels somewhat biased rather than objective.
As for drop-off, only time will tell.