My Apple Gift Card is showing invalid I bought it at the store

Never post pictures of your code, in addition to your receipt on a public website such as this. All you needed to do is sign in with your Apple Account/Password and the same is true for anyone else to view what you posted. All it would take is a bad actor to resolve the problem themselves and you would be at a loss.

For your situation, review the information provided here and there is a link to Contact Apple Support where you may be asked for that information where it is viewed by Apple and not everyone else. Usually the Invalid error message is due to a character being read incorrectly if using the camera or typed incorrectly, but either way all the information you need can be found here:

If you can't redeem your Apple Gift Card, App Store Card, or App Store & iTunes Gift Card - Apple Support

No one here is an Apple employee. No one has access to your personal or financial information. Please follow the steps in this Apple Support article. 

If you can't redeem your Apple Gift Card or App Store & iTunes Gift Card - Apple Support

If after reviewing the article, and following the directions in the article, you need additional assistance please follow the link below to contact official Apple Support. 

Contact Apple Gift Card Support

If you receive a request for payment using Apple Cash, or If you believe you are the victim of a scam, please contact Apple Support and report it to local law enforcement.

About gift card scams - Apple Support

You may also report the scam to the FTC Complaint Assistant and to the FBI’s Internet Crime Complaint Center

If you receive a request for payment using Apple Cash, or If you believe you are the victim of a scam, please contact Apple Support and report it to local law enforcement.

be careful because they are now cracking down on scammers who ask for your giftcard