In an internal document, Apple states that it has identified an issue with the logic board of a “very small number” of 2018 MacBook Air units. The company will replace the logic board of all such affected units for free.
Apple is not disclosing the issue publicly, though it is contacting all affected MacBook Air customers over email to inform them that their device is eligible for a main logic board replacement. Right now, if you own a 2018 MacBook AIr and want to know whether it is affected by this logic board issue or not, your only option is to take it to your nearest Apple Store or Authorized Service Provider.
You don’t need to necessarily rush to your nearest Apple Store with your MacBook Air though since it will be eligible for a free logic board replacement for 4 years from the date of purchase. However, if any kind of accidental damage prevents the logic board replacement, Apple will require customers to pay for the necessary repairs.
The MacBook Air repair program comes hot on the heels of the 15-inch MacBook Pro Battery Replacement program from Apple which affects over 500K+ units. It is likely that the MacBook Air issue affects a very small number of units and is not that serious which is why Apple has not announced it publicly.