Yes, recoil reduction, not elimination, is the most a muzzle brake can achieve. Without a brake, once the bullet leaves it is followed by gases and particles equal in mass to the powder charge and because gas is less dense than lead, it accelerates to a velocity faster than the bullet goes, passing it until it slows. That gas and particle jet comprises an impulse rocket pushing to the rear, and the force it adds to recoil is significant when the residual pressure at the muzzle is high and the mass of the powder charge is significant. In some overbore cartridges, the "rocket effect" (also called "after effect") actually produces as much as 60% of the total recoil, exceeding that caused by the bullet.
With a brake, the idea is to vent the high-pressure gas perpendicular to the bore so the pressure that creates the rocket effect is lost just before the bullet clears the muzzle, eliminating it. Some brakes just vent gas in all directions perpendicular to the bore for that reason. Some direct the gas, as yours does, to try to help control the gun's movement. Yours directs it up to mitigate muzzle rise. The clamshell types and their variants direct it along a shallow rearward angle so the rocket effect pulls the gun forward. That's the only type that tries to mitigate bullet-caused rearward momentum. All of them have the problem that venting gas in any direction but forward raises the sound level for the shooter and especially for people around the shooter. You don't want gas directed at your loved ones, as that makes the loudest sound.
The SAAMI recoil formula includes the rocket effect, and you can try out the calculation with your loads to give yourself some insight into the problem. Note that when you download a cartridge, the muzzle pressure becomes lower, reducing rocket effect and causing muzzle brakes to become ineffective, as they have no rocket effect to mitigate.