Fall names disabled was implemented on Steam to curb exploits to the UI and to prevent displaying offensive language.

Fall Guys Names Disabled to Prevent Naughty Words and Hacking

Shortly after the matchmakers came back online, players found that their custom names had been disabled from displaying. Instead of the player name, the game simply shows a generic "Fall Guys XXXX." Previously, the game had issues with names injecting HTML code that messed up victory screens.

Slowly coming back online...

Changes:
? Optimisations and enhancements to the servers for the weekend!
? Temporarily disabled custom player names on Steam as players were using exploits to break UI and display offensive language
? Fixed store to prevent hacking crowns/kudos

— Fall Guys ? (@FallGuysGame) August 7, 2020

There was also a glitch that let players get around naming restrictions on Steam to somehow exploit the Fall Guys store for more Crowns and Kudos.

Both glitches revolved around naming exploits, and as such they've been disabled as Mediatronic fixes the problem.

Don't worry if your game isn't displaying your usual username. You'll still be logged into your account, but your name will just display as "Fall Guys XXXX" for now. It's unknown when names will be going back up.

Fall Guys: Ultimate Knockout is a battle royale platformer that pits 60 players against each other on an obstacle course. The game was a huge success at launch, though Mediatronic is having trouble keeping up with the traffic.

Fall Guys is out now for PS4 and PC via Steam.