I have purchased new iPhone 14 plus yesterday

Click on this link to read how to update your proof of purchase --> Update your proof of purchase - Apple Support

To update your information contact Apple Support by phone. Tell the advisor that you need help with your Apple Limited Warranty or AppleCare plan expiration date.

Here’s what you need when you call:

- Your AppleCare agreement number

- The device serial number

- Your sales receipt

If you bought it from a third party reseller and not from an Apple authorized store then the date will be the date the reseller purchased it from Apple.

Where, exactly, did you buy it?

Sounds like you purchased a gray market phone from an unauthorized seller.

The warranty clock started ticking when the device was originally sold by Apple or an authorized retailer.