I think that the fake Danny Devito death is a funny joke and I'll explain why.

Hexbear has a culture. Hexbear has it's own memes and references and stuff like that. The fakenews comm uses references and memes from Hexbear culture to create a story, an alternative world.

One meme on Hexbear that I've seen is like the idolization of Italian people or the Italian mafia. I believe this meme stems from Chris Cuomo in 2019 saying that "fredo" was a slur for Italians equivalent to the n-word. This is like obviously an absurd thing for Cuomo to say and chapo made fun of him for it. Then a meme sort of developed that "Italians are the most oppressed race" meme, making fun of Cuomo and other white people. Hextube started watching a lot of mafia movies and hextube made a bunch of mafia emotes exclusive to hextube. Danny Devito is partly of Italian descent and he has acted in more than one Mafia movie.

Another element is that Danny Devito is perceived as a left-leaning guy. Danny Devito campaigned for Bernie Sanders in 2016 and in 2020. Danny Devito is a beloved figure in general. Reddit loves Danny Devito. Chapos love Danny Devito. You probably love Danny Devito, which is why you are upset about a fake story.

The third element is Melina. Melina also loves Danny Devito. Danny Devito plays Frank on Always Sunny. Melina is a super fan of It's Always Sunny in Philadelphia, even watches their podcast as well as the show.

In my opinion, humor is a subversion of expectations. You expect one thing to happen, but then something else happens, and the surprise that you experience causes you to laugh. I've established that Danny Devito is a beloved figure and that Melina loves Danny Devito. The expectation for me is that Melina would create a fakenews post which idolizes Danny Devito. The real outcome is that Melina creates a fakenews post which kills Danny Devito. Melina kills their own hero in fantasy. I think that is funny.