For me it was Okami. I remember you do a ton of shit to get to a certain boss which I thought it was the end, only for it to reveal that there was a loooong path ahead.
Other than that, maybe cyberpunk? I was surprised after all that stuff you do in the beginning just to see the titles pop up
The prelude of AC Odyssey. I remember having put in like 20 hours of game time when the intro credits started rolling. Was definitely a wtf moment for me