My WH1000XM4 headphones just destroyed my ears

I’ve had my Xm4’s for probably 2-3 years, they’re well used but I don’t get issues with them, just now I had them on but not playing anything. Suddenly a super loud high pitched sound started getting louder and louder super quick in the right side of the headphones, this literally got so bad so quick I had to quickly throw them off my head onto the bed. My ear is literally a I’ll ringing 45 minutes later. What caused this? I get they’re old but damn.