Replace charging port or battery ?

My iPad Air 2 suddenly stopped charging . Cable does nothing . I use Anker cable and Anker IQ plug . Always fine . I used 12W plug doesn’t make difference . iPad kept restarting and booting . I made hard reset . Then Recovery mode made the iPad to charge . I upgraded to OS 15 . Same issue . I did Reset Settings . Now the iPad charges when I turn it off . Any cable any plug . When battery is low I turn it off . Put cable there . iPad turns ok charging . It’s charging hours with little % . It stopped at 82% . Is this charging port or battery issue to replace ?