
Engadget reports some users of late 2013 to mid 2014 13" MacBook Pro laptops are stuck with a black screen after trying to update to Big Sur:
We’ve asked Apple for comment. The company has asked at least one owner to send their system in for service, while another said Apple’s engineering team was aware of the problem. For now, at least, you might want to hold off on updating your older 13-inch MacBook Pro.