Find some other activities. Tee-ball, soccer, swimming, cub scouts, anything that involves interacting with other kids without technology.

Just ban it. My kid is in that age group and roblox is banned. Her feelings on the matter are irrelevant. I don't know why people hand wring about "oh they'll be left out". Oh well? I'm a millennial. I remember being just a poor kid at a school with kkds much wealthier than me. There were a lot of things my friends had that I didn't. Like a cellphone. I wasn't in the group chats and somehow I still survived.

My kid is disappointed, but it's fine. She has friends play the games she does have and she has a lot of other games. She had a lot of other ways to socialize with them. I honestly don't see roblox as different than any other social fad. Roblox is just the default digital hangout spot for kids, but it doesn't have to be for your kid's friend circle.