Replaced brake booster 1 1/2 years ago &this is the 2nd time now that when useing the break it makes a hissing noise &at times pedalsucks to the floor

Toyota Camry LE 4 Cylinder 2007.

A year and a 1/2 ago I replaced my brake booster and ever since then (this is the 2nd time now) my brakes don’t work very well they make a hissing noise when I apply the brake and at times the brake pedal will suck to the floor.

I don’t know if I did not install the new brake booster correctly or what it could be? The 1st time it happened a friend did something to fix it, but I am not sure what they did. Its been about 6 months now since the 1st time it happened and was fixed til now.