It's not necessarily a 'problem', as you put it. Technically, it's a 'Slide Stop' lever (lots of arguments/debates over this), and
primarily used to lock the slide in the rear position. When the slide is locked to the rear, just use your off-hand to release the slide by pulling it 'smartly' to the rear and letting go forward. No biggie.
P.S. Your new
handgun/pistol/sidearm is only a WEAPON if you use it as such.