Overwatch 2 finally launched yesterday, but there were a lot of issues for players when they wanted to connect to Blizzard servers. It was thought to be a massive crowd first, but Blizzard confirmed later that they were being targeted by some mass DDoS attacks.
President Mike Ybarra confirmed this on Twitter, but did not share any possible expectations about when the problem can be solved.
The attacks did not simply lock everyone out, there were some players still able to play. But if you were unable to join, this might be a possibility. Besides the DDoS attacks, some players were having other issues such as merged accounts causing errors and some cosmetics not appearing in their collections.