most people are focusing on the free labour roblox is extracting from kids but from the article:

Further claims stated, according to Turkish media, that Roblox hosted virtual parties promoting pedophilia and that “robux,” the platform’s virtual currency, was being distributed by bot accounts to encourage children’s involvement in these activities, and excess presence of gambling sites and their predatory tactics.

so it looks like roblox was banned because of bad moderation in regards to gambling and sexual predators, both of which are massive issues of the platform. overall i think this is a good move which hopefully will push roblox to do better.