Roblox has minor problems every now and then on the website. It can also be laggy with bad internet or on a old device. To add on, there could be bad content inside some of the games inside of rblx such as inappropriate content and outfits, so I would recommend it to more mature older kids. To prevent your child from participating in inappropriate behavior check their rblx account, by signing in on your device to their account or look on there device (w/o kid knowing so they dont change it up)