That’s because the device is telling ROBLOX it’s a touch screen. To ROBLOX, touch screen equals tablet or mobile platform. This also happens with touchscreen laptops if I remember correctly.
The solution would be to check for the lack of a mouse, instead of checking for the presence of a touchscreen.
One design that I think would work would be to have a cookie that says tablet=true if a touch event has been detected but a mouse has never been detected, tablet=false if a mouse has ever been detected. If neither have been detected, there would be no cookie, and it can default to assuming a desktop to be safe.