Hear me out... they are both flying creatures. AND kinda look a little similar ... thats all I have. bye. JUST KIDDING you can see Kirby riding flappy in the canceled Kirby game for the gamecube with became Kirby's Return to Dreamland AND assets were taken to use on air ride, and flappy is in air ride. unless that image is fake because I don't see flappy in the old trailer but I don't think you can ride flappy in Kirbys air ride, plus I doubt its fake because why really would someone do that like for what purpose would an image with flappy specifically be fake. thats about all I have
UPDATE: Halcandra has variants of dreamland enemies and landia can only fuse with the crown supposedly, we never see them fuse without it, so what if flappys are the dreamland variant of landia, and other landia's exist(ed) and are much weaker because they don't have the master crown, but you might say "but oh! there still powerful when split apart in the fight" and to that I say they still have the master crown, my point is not all are this powerful and would be basic enemies. So the other lands must have gone extinct because that place is an absolute WASTELAND. I'm running out of ideas aren't I :P