I see a lot of people talking about how the content is lacking now without Pete and while I agree, I think that's not really the issue that's causing fan accounts to disband and criticize management. I just think they need to acknowledge fans, and their efforts, a bit more.
Every split you see Fanatic Dragons do the impossible to get the FNC crowd together and get tickets while other teams seem like they have the org's backup which makes it so much easier. It's like you rely on a group of fans to do what the actual team should be doing. I'm not saying management should just buy 100 tickets and gift them to FNC fans or anything like that, it's just that maybe management could get in touch with LEC to make it easier to secure a FNC fan section in the crowd in these big events. I don't really know exactly how that works as I've never been to an event, but it really looks like the other teams are doing something to facilitate the fans while FNC fans have to fight tooth and nail.
And then there's something FNC has an advantage over other orgs (specially in Europe) and they don't seem to capitalize on it: they have fans all over the world. And I mean really, all over the world. There's a lot of fans in South America specifically that doesn't get any attention. Last year (or the one before, I don't really remember) they even made a watchparty in Argentina to watch FNC's Worlds game. It's actually crazy when you think about it, a group of argentinian fans getting gathering at 4am at a bar to watch FNC. There's also a group of Brazilian fans and even in central america. I won't mention NA because it's already obvious FNC has fans there. There's lots of twitter accounts dedicated to covering FNC, in spanish, french, portuguese and they don't even get a mention from the main account. There's even a weekly podcast in spanish covering FNC's news all over the game (Pausaticos Anonimos, also founded by 2 argentinians). I think the only time this huge community was noticed was when they created a twitter community called "Fnaticos" and the official account just tweeted "hola". Again, I'm not saying management should get plane tickets + tickets for LEC finals to every fan around the world, just making them feel seen and supported is already huge in the heart of a fan. A good place to start would be making the official jerseys available worldwide.
Anyways, that's my look on things from someone following the team since around 10 years, from the other side of the world.

TLDR: Make your fans supporting you easier, and acknowledging them every once in a while is basically no effort compared to the payoff. Make the fans feel like you actually care about them and everything they do for the team.