DB has a fantasy/sci fi world where sci -fi elements such as aliens was not totally out there espescially given this is a verse with tech like capsules, Cyborgs/androids and flying cars exist. So sci-fi was always there from Chapter 1 when Bulma showed up in a high tech motorbike. Could the alien thing have been set up better? yes but it was not completely out of left field. to introduce sci-fi
espescially given the lore of Goku and piccolo was never set or grounded in anything besides surface level inspiration of Journey to the west and eastern mythology in the aesthethic department. They were never established factually of being what they were assumed to be(monkey king and a demon). It was all assumption and speculation by reader and even the characters,. And the sci-fi element cleared everything up
As for YYH, even with the demon element being there that does soften the near dues ex machina. togashi pulled with the demon ancestry thing. Worst of all it was used as a asspul powerup to defeat a villian with no foreshadowing or any buildup. It was just Togashi bringing it out as a resort to resolve the arc
im not gonna address some of the other stuff cause your just nitpicking at what you dont like. and yes you can say "its just the characters" as characterization is not the only way of writing. You have the story itself, themes, and execution. Which DB did better than YYH.
you can go on about DB's lows, but YYH has lows to.On top of that, This series ends has one of the worst endings, and yet according to some of yall this is better than DB. Man foh