uploading nsfw images is completely fine on discord as long as the community will be only for those who are 18+ by having moderators to kick who identified themselves under 18 and by simply age restrict channels , and getting banned on discord isn't possible for uploading nsfw content in channels aren't age restricted, you will just get disabled for posting such content publicly for all ages, I think that's what happened to you since you didn't know the function of making a discord server, and discord itself supports such work of yours as you may get your server verified since you own a popular game and you picked discord to make a community for your game
and again, if you want to create a server for your community and to make it easier for them to feedback. I am at your serves