This update, known as KB5006674, delivers security fixes – MS doesn’t say what that entails – along with a fix for those with Intel Killer and SmartByte networking gear suffering from packet drops. There’s also a Servicing Stack update for Windows Update itself.
Windows 10 users get all the same stuff, via update KB5006670, along with a notice that Windows 10 version 2004 (aka 20H1, or the May 2020 update) will reach the end of servicing support on December 14, 2021, and users should update immediately.
Other issues with Windows 11, such as the occasional non-starting of Virtualbox VMs, remain unpatched, but the elephant in the room has to be the Ryzen cache latency and core scheduling bug, which sees AMD chips slowed by up to 15% under the new operating system. An article on the site Techpowerup claims that the new patch actually makes this worse.
An AMD statement confirmed that a new driver will be available this month to address the core scheduling problem, and a cache usage fix will come via Windows Update, also later this month.