Instead of charging, my iPad is losing power

Check that the power outlet has power, that there is no fuzz and no debris lodged in the charging socket (use a toothpick or a plastic barrette or other flexible and non-conductive tool to remove any foreign matter found), and confirm that the charging cable and charger both work; swap for known-working cables and charger, if possible.

Force a restart of the iPad, too.

… Force restart iPad - Apple Support

Then check with Apple Support. Use the Get Support link in the upper right of this webpage to discuss this with Apple.

It may be time to make an appointment at the nearest Apple Store for battery replacement...

Apple Store - Find a Store - Apple