MILAN—Anyone whose virtual alter ego is wandering around the Roblox online game platform these days might run into other avatars sporting Gucci handbags, sunglasses or hats.

MILAN—Anyone whose virtual alter ego is wandering around the Roblox online game platform these days might run into other avatars sporting Gucci handbags, sunglasses or hats.

Roblox is implementing fixes for a chat moderation exploit that resulted in a wave of automatic bans, but the offenders say there’s more to come.