iPad not charging with the usb c-usb c charger.

These support pages should help with troubleshooting:

Charge and monitor the iPad battery - Apple Support

If your iPad won't charge – Apple Support

Troubleshooting generally requires substitution of the Power Adapter and cable for another known-good item.

If you continue to experience difficulties, you might be best advised to visit the Genius Bar at your local Apple Store or Apple Authorised Service Provider (AASP) - where the technicians will be able to test and assess your iPad, Power Adapter and cable(s):

Genius Bar Reservation and Apple Support Options - Apple

Whilst it is always worthwhile to check that the charging port is free of debris, never (ever) probe the port with a metallic object. The delicate electrical contacts can be easily damaged - and if short circuited may cause irreparable damage to your iPad. If you need to dislodge debris, use a fine wooden or plastic toothpick, with good light, being careful to not damage the contacts or retainer springs. Better still, the technicians at an Apple store will be happy to assist.

DO NOT use ANYTHING metal inside of the Lightning connector port to attempt to clean it out!

You could damaged or short out the port!

Use something non-metallic, like a wooden toothpick or a thin piece of plastic. Just something NOT made of any metals!

If NO success, you need to search online for your nearest, “local” Apple store location and call contact phone numbers and call to make an appointment to have your Apple iPad diagnosed and options presented you.

Failing that,

You need to contact Apple support via the contact support link located at the upper right hand corner of every Webpage of these Apple support communities.

Use the Hardware Repair & Battery usage & Charging support categories.

OR

by installing and using the Apple Support app found in the iOS App Store.

Tap the iOS App Store link below.

https://apps.apple.com/us/app/apple-support/id1130498044

OR

Call contact Apple via the support numbers found in the link bekow.

Contact - How to Contact Us - Apple

Tap the link below.

https://www.apple.com/contact/

Best of Luck to You!

i had issues a few years back with very inconsistent charging. I took tweezers into where you insert the charger and I managed to remove literally a little bit of fluff that got stuck in there quite tightly somehow and then had no charging issues with the device again. Might be worth a try. The more you insert the charger the more impacted something like that may be inside