I have had these Life A2 NC’s for about two months now, I use them at near full volume for two to three hours a day, and the right ear now is about half as loud as the left one, making it difficult to hear music above everything else with just the right earbud in. The noise canceling in the left ear has seemed to stop, I can hear far more out of the left ear than I did when I got them.
Life A2 NC volume difference between left and right ear
You probably blew the speakers in them. That’s one way to ruin anything with speakers. That’s why I have ANC on and volume low. And high volumes can make you deaf or have tinnitus and ruin the speakers in the earbuds, headphones, whatever has a speaker.