There's a ads sensitivity multiplier in the config file.
mouse_ads_yaw_ads_multiplier = "1" // 0 to 30
mouse_ads_pitch_ads_multiplier = "1" // 0 to 30
75% means it distance matches to the angle at 75% distance from center to monitor edge. If you have 1 ads multiplier, 75% relative match, then hipfire and all aims will require the same mouse distance to move purely horizontal to whatever reference point is at the 75% mark. Check the monitor distance match video to see what its suppose to do. It's the ads multipliers above that drop the sensitivity by a flat amount.
Past cods scaled proportionately with the change in fov, which is legacy or 0% relative. If you played a past cod at 90 (4:3) fov, then aiming with smg dropped the sensitivity value by 52.0567%, and ar was 46.6308%, both scaling proportionately with the change in FOV. Whenever you aimed down sights with an SMG, everything scaled by 100/52.0567= 2.144507. Since the rendered frame is 2.144507x zoomed in, enemies and geometry looked 2.144507x larger on the screen, enemies moved 2.144507x faster across the screen, etc. The sensitivity scaled by 1/2.144507 to keep the input sensitivity unchanged. The distance to rotate angle per angle changes by the zoom factor though, so the distance to rotate 360 degrees will be 2.144507x larger. If it kept the 360 degree distance, then the input sensitivity would actually not be identical, but amplified. Same with any relative distance setting above 0%, they are amplifications in sensitivity. Use legacy or 0 relative if you want it like every other cod.