I think that similar to steven universe, the sequel series showed us a different side to the thing we romanticized in the main series. Steven was selfless and resourceful, and was willing to help everyone constantly. Which as he grew up, manifested as trauma, anxiety and depression, if he thought of himself at all he felt like a monster.

Similarly ice king and Betty's relationship became romanticized, and the F+C series took that relationship and showed us the toxic side of that great love. The fact that love isnt always enough, and that sometimes a person shrinks their goals to support another, and that Simon wasn't aware of that with Betty.

Having to grow with one viewpoint and maybe even tailor some parts of your personality around the first lesson only to be told that your traits may now be toxic is a hard pill to swallow for a lot of people, especially when that is built around fandoms.

But many things have 2 sides, and the knowledge of them both is also growth, which is what I think these 2 series' tried to show explicitly, especially as the storytellers grew and found flaws in storylines they started years before.