If you're playing in "Fullscreen" mode which in current Destiny 2 Edge of Fate state it's actually "Borderless Fullscreen" and that what's causing the input latency or lag. They removed the Exclusive Fullscreen mode as you probably noticed already. Borderless fullscreen mode uses something called "Composed: Flip" in Windows, which routes frames through the Desktop Window Manager before displaying them, this is what is causing the input lag and the game not feeling smooth. Exclusive Fullscreen, the game used "Hardware: Flip". The frames went directly to the screen and not through Destktop Window Manager, no middle man per se and the game felt smooth as butter. Hopefully they fix this.