It's the nature of the beast
If your outboard exhausts through the lower unit, past the propeller, then in reverse the prop is pulling on a water/exhaust mixture less dense than the water it pulls on going forward. My Hunter Whisky II has a 9.9 on her stern, port side mount. You learn to compensate. (You'll never be able to run into a slip and hit reverse like the power boats do.) You learn stuff such as engaging reverse at just above idle while still tied by a line or two in the slip. As tension builds on the dock lines, release them. You'll have immediate momentum. Stuff like that. Good luck - you ain't alone.