Scoob and the gang have an existential crisis.

Monsters and ghosts have been real in the Scoobyverse since 1998′s Zombie Island.

I think they’re ignoring that, and Mystery Inc…

They are. Despite the art style, this is set in the original cartoon, specifically a 1970 episode “A Night of Frights is No Delight”

And technically speaking, calling it the “Scoobyverse” is kind of incorrect since the majority of Scooby Doo cartoons are set in seperate continuities.