TL;DR: Nintendo decided to do a cool thing for their game's competitive community and give the tournament winners a custom cosmetic. The winning team is these guys called "jackpot". Some time later, a large quantity of discord messages are leaked that consist of the whole team saying a whole bunch of racist shit about black people. Now, Nintendo is removing the custom banner and disqualifying Jackpot. It's currently unknown whether the runner-up team, Phantom Thief, will be given the trophies or a banner.
Discord broadcasts everything including direct messages to the world (in such an invasive and incompetent fashion that somehow completely random people have been able to hack into your shit with tools they can get off the internet at various points and probably still can) and makes you jump through hoops and dead links to access it
Plus they'll try to ransom your account and demand a phone number (not a secure method of communication btw) to deanonymize you if you sign up with an email alone