Mouse control is a little weird in this game. It feels broadly okay most of the time and then a little off in others, probably due to the negative acceleration.
I did see something about there being a registry key to toggle mouse smoothing - \HKEY_CURRENT_USER\SOFTWARE\Guerrilla Games\Horizon Forbidden West Complete Edition\Input\EnableMouseSmoothing. But when I turned it off, it just made the mouse super slow, I couldn't really tell if it was any better.