Battery health glitch?

Can someone please explain why my battery health went from 89 to 77 in a matter of 5 minutes. It literally just happened right now and I'm livid. The phone couldn't identify the battery for a while so I restarted and reset the iphone 11, only for it to tell me it's 77 and NEEDS SERVICE. I BARELY USE THIS PHONE, BARELY!!. Please what can I do to fix this?

Battery health glitch?
 
 
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