Apple has discovered a logic board issue with 'a very small number' of 2018 MacBook Air units, according to an internal support document obtained by MacRumors.
Apple will replace the main logic board in affected MacBook Air units, free of charge. Apple will also send an email to affected customers to let them know that their notebooks are eligible for a main logic board replacement. Apple did not provide any specific details or symptoms pertaining to the "issue."
If you're experiencing an issue with your MacBook you should contact support. When your serial number is entered into Apple's internal repair system, a message will tell technicians to replace the logic board.