The creeps are only part of the problem. The platform itself is deeply exploitative and harmful. It's full of "you can make games and get rich" messaging that's just a lie. To say nothing of even if you are successful, they will take a staggering cut, and may not pay at all.

Keep your kids as far from Roblox as you can.

Strongly recommend against Roblox, as it's got a pretty long history of being predatory towards children through marketing, sales cuts, etc.