I'm not sure of the nature, but definitely closer to the former. It looks as if the game is sometimes straight up not reading my mouse click input on on one tick/frame, and sometimes takes time to read the "mouse button release event". To give a more concrete example (the game in question is squad), when my rifle is set to semi-auto mod and I try to shoot, it will sometimes straight up not shoot, even tho I clicked left mouse button. In automatic mode, clicking just once will shoot a burst, while supposed to shoot just a single bullet. This issue doesn't seem to be happening consistently so it definitely won't be too much an issue but I'm still curious.