Why has my iPhone 12 stopped charging with third-party chargers?

There are genuine non-Apple cords, and counterfeit Apple cords. The counterfeit cords can actually destroy your iPhone→Why Counterfeit Lightning Cables Kill iPhones - Motherboard

The way to resolve it is to only use Apple cords or cords certified as Made for iOS (MFI) from reputable manufacturers such as Griffin, Anker, Mophie, etc. NEVER “gas station”, car wash or supermarket cords. Amazon Basics seem to be OK also; I use them.

Hi. In my opinion go back to the place where you bought these non-apple chargers.

Otherwise buy Apple chargers and cords, I know they are expensive, but in all the years I have used them, they have never failed me.

chrisky307 wrote:

Hi. In my opinion go back to the place where you bought these non-apple chargers.

Otherwise buy Apple chargers and cords, I know they are expensive, but in all the years I have used them, they have never failed me.

I agree. And expensive is relative: An Apple cable is $19. To protect a $1,000+ phone, it's a bargain.

“… but in all the years I have used them, they have never failed me …”

A very significant and relevant observation.

Now that you mention it, I’ve NEVER experienced an Apple power adaptor failure.

And I’m STILL using a couple of 5w “ice cubes” from the iPhone 5 era.