It just randomly turns on for no apparent reason. It appears in the bottom right of my screen. This also happened for a game i played earlier this year. Let me try deleting roblox and if that doesnt work, i'll come back here.
Back, just deleted my roblox player, reinstalled, and nothing happened. My webcam is still showing.
Update: Just found a solution. Found out it was not Roblox, but in fact, the computer capturing my webcam from the NVIDIA control panel. I just disabled camera use and my webcam is not showing. It worked!