In my case, I did the install using Command Center about a week ago. At the end of the installation, the Sonar indicator was green and all subcomponents were green. Yesterday the Sonar indicator was yellow, with all sub-components green. The message said an update is available. When I performed the update, it displayed a bunch of activity downloading and installing files. At the end of the process, the indicator had changed to green. Happily, Sonar continues to work. The About screen shows version 21.00.01 Build 254 x64. Could be that is what I had all along, but the file activity seemed to indicate something substantive was happening. So I'm still wondering what changes, if any, happened in this process. My "Downloads" folder does not show any new files from this process (perhaps the "update" files were deleted after installing), so no clues there.
Maybe the content of upcoming changes will be made more obvious in the future. Most helpful would be some text describing the changes (bug fixes, feature additions, etc.) so users can make informed decisions about timing and possible benefits.
If I'm the only one who got this update message (and files installed with possibly no actual changes), it could be a symptom of some obscure glitch in the CC system instead of an actual update. I'm hoping we'll learn more when the regular work week resumes.