Here are some hot takes...
Most of the Slenderverse are just remakes of the big three, not even making unique things. Only in recent years we have seen diferent stuff, but once you see MH, TT or EMH, you kind of see them all. And most of the time aren't even that good.
Zalgo being reduced to a demon like creature with cults and a mythology reduced his concept in such a brutal way... less is better.
Same with Slenderman. The first two images are the remembered because the rest is just an overpowered monster. Again, less is better. Too many habilities make him look lile an omnipotent god.
Creepys like Jeff, E Jack, Jane or Toby aren't really bad stories, but they are so badly written that affects everything on it, making them look like dumb slasher killers.
That being said, we gave too much credit to what were initially Self Insert OCs.
You like it or not, the unfortunaly Slenderman Stabbing incident made the character an atemporal and culturaly important character. To the point that even people outside the internet knew about him.
The proxies are actually a cool concept for making OCs. The killers felt like repetitive and low polished Jeffs, but the lack of identity in proxies are kind of the point when we see how Slenderman is suposed to act with them. They are now puppets.
Any Creepypasta character creator have to face the fact that they will not have control on how the character is gonna be in the community. The lack of canon could be helpful or damaging to it, but it is inevitable. So if someone gets angry because of that, just keep with your own version and that's it. Deal with it.
Charlie's story in Slender the Arrival took too much space in the final game that I'm still even surprised the devs didn't just expanded on the original cast instead of taking over 80% of the game with a new story.
Slenderman should not have tentacles in the literal sense. He is not an octopus or Venom, it works better if the extra limbs are variable, like if someone have diferent interpretations on what they are seeing. Tentacles, branches, spider legs, extra arms, you name it.
Jeff's remakes of him being deformed are trying too hard. I know it's imposible to have white skin after a burn with flames, but have you consider Skin transplant?
It is fair if you wanna put Masky and Hoodie as proxies. After all, they were the ones who started all. What I don't like it's when proxies are too powerful, like Revenant, Redlight or Collective type of proxy. They are slaves.
Most of the creepypastas on the internet aren't even creepypastas. They are just horror stories that could be published anywere and are only famous because they were on the internet. I think a hood Creepypasta is that one who uses the internet format as part of it, like, you can't tell this story without the internet. Examples: Ted the Caver or Seed Eaters.
The Creepypastas without a concrete author and being 90% made by the comunity and popular perception could enter this format too, like The Rake, Slender, or heck even Jeff at some extension, Sesseur have nothing to do with the current state of the character.
People like it or not, but the fact that some went angry because the 2018 Slender movie didn't portrayed him good just shows that the statement of "Being a character that you can use whatever you like" is false, because we know now how to use Slenderman at his finnest, what are his limits in storytelling and what to do with him. Having him being an ancient god, eating organs or ripping limbs off, showing feelings, or heck, even being able to be defeated, just feels wrong. Parodies aren't included on this because those are meant to mock on the concept.
You can see the diference with some characters that are well fitted on this abstract concept, like the King in Yellow.