As others said, the gun is fine. There are actually shitty rubbers out there that freeze and then crack.
So just seeing you got a problem, take apart everything, clean everything like sears, valve knocker, and re-lube except for mags.
Even though the sears and valve knocker, have nothing to do with the shots like hitting hard and soft, clean it.
What I think is your BBU, the piston head o-ring is creating friction and have seem to froze up in your nozzle.
Take your slide apart and test the nozzle. Move it out and let it return back in.
If it's really stiff, take it apart, re-lube and try again.