My immediate answer - Sonic fans.
I don’t really know what Sega and the Sonic Team can do anymore to make these fans happy. They’ve revisited the classic formula a few times, they tried going modern routes, they tried 2-D sprites in some entries, they try going full 3D and whatever. Nothing ever seems to be enough and that’s even when they’ve tried listening to the fanbase a few times.
Nothing seems to matter, regardless. The fans will find something to be upset about with Sonic. Anything.
A bit of a hot take… bigger communities tend to get harder to please, regardless of anything else
I saw a few gacha game communities (please don’t judge me lol) grow in real time, because gacha games need as large as a player base as possible for their business strategy (which is a separate topic)… Saw the level of toxicity rises in real time as my main game’s community get bigger. Like the community literally went from being okay with just about anything to arguing over the weirdest details on character designs and complaining about every live-service event. And then there’s all the rumor about communities of Hoyoverse games… including once when someone almost murdered the company CEO over a bunny girl event (I’m not making this up)
Among similar sized ones I’m not entirely sure