AWS (Amazon Web services) was the culprit. Amazon isn’t just a seller of goods. It also provides extensive web services to large companies, some of whom then provide internet to the consumer.
Some of the larger companies impacted were Snapchat, Venmo, Roblox, Xfinity, Amazon prime, Duolingo, Whatnot, Rainbow Six Siege, Coinbase, Goodreads, Ring, The New York Times, Life360, Fortnite, Apple TV, Verizon, Chime, McDonald’s App, and a host of others, many of which affected sites like SF.
Initially it was thought to be a major hack, but apparently it turned out to be some kind of internal software glitch.
The problem was thought to be fixed, but then it went down again, so there were more massive problem solving efforts which stabilized AWS which then fixed consumer issuers, hopefully permanently.