You think normal people can't tell? Go turn your monitor to 60hz in your video options and move your mouse in circles on your desktop, then go turn it back to 144hz or higher and move it around on your screen. If an average csgo or valorant player where to play with framegen while the real fps was about 60 and the rest of the frames where fake, it would be so completely obvious it's almost laughable. That said the 5090 can obviously run those games at 200+fps so they would just turn off any frame gen stuff. But a new/next gen twitch shooter will for sure expose it.