I don’t think it’s a matter of underestimating demand. Granted, I don’t know anything about scalability in terms of infrastructure for this stuff, but I figure they may have just figured it not worth it to scale things up for a demand that will fix itself within hours.
In comparison though, it was basically one and done. Assassin’s Creed is a fairly long running franchise, God of War and Mario too technically, paired with bits of nostalgia. Palworld can always improve and still get attention past the first month.