Apple has just released an update to Big Sur, bringing it to version 11.2.2. This is an urgent and out-of-cycle fix which Apple says “prevents MacBook Pro (2019 or later) and MacBook Air (2020 or later) models from incurring damage when they are connected to certain third-party, non-compliant powered USB-C hubs and docks.”
The update is 2.6 GB for Intel models, and 3.1 GB for M1 Macs. Yes, it really is that huge, and is intended to be installed on every Mac model running Big Sur, it seems.
There are no changed version or build numbers among bundled apps, nor in the System/Library folder, indicating that this update brings essentially no significant change to Macs other than the MacBook Pro and Air models affected by the bug described by Apple.
The Darwin kernel version remains at 20.3.0. However, T2 models have an iBridge firmware update which takes the version number from 18.16.14346.0.0,0 to 18.16.14347.0.0,0.
The update downgrades MRT to version 1.72. Unless your Mac updates itself shortly after the macOS update completes installation, you may wish to run SilentKnight to bring it back up to date, the way it was before 11.2.2 was installed. Sigh.
Unless your Mac is one of those which Apple reports as being susceptible to damage, you may wish to delay this update until you have a couple of hours in which you’ve got nothing else to do. Quite why Apple is wasting so much bandwidth and the time of so many millions of Mac users to do the square root of diddly-squat, I have absolutely no idea. Maybe they need to get out more often?
(Updated with the details – or lack of them – of the changes in this update, 0220 UTC 26 February 2021.)