Apple pencil 1 battery drop to 6 % in 2025

Can anyone tell me how to fix this type of problem with pencil 1 that my pencil battery was 37% and when I plugged it to charge with its adapter it dropped to 6% again i unplugged and plugged the pencil into adapter it showed 9 % then again dropped to 6 % . So i shutdown the ipad and turned on the ipad it charged normally but took above 1 hour to charge 88% .is it a software problem or hardware problem please