resolved, was 'registry tweak to vertically stack "peek" icons over taskbar app icon'

On 5/22, I posted the following registry tweak to vertically stack "peek" icons over taskbar app icon - Windows 10 Help Forums
Then I received friendly helpful guidance that there was an Windows 11 Forum which would be a better place to ask.
I was able to resolve the issue before making my way here (the fix: uninstall KB5058411, which had been installed on my PC late on 5/21).
I hope someone at MSFT sees that KB5058411 breaks Shawn's excellent rgy tweak and fixes that breakage with a new KB.
Here's the original post:

For years I've been using Shawn Brink's excellent rgy tweak for "Taskband Thumbnails" at

Change Taskbar Thumbnail Threshold to Show List in Windows 10

This registry tweak is to add a DWORD value (named NumThumbnails, with a value of 1) to this key:
Computer\HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Taskband

Last night my Windows 11 PC was updated to Version 24H2 (OS Build 26100.4061) and Shawn's rgy tweak stopped working.
Another PC running Win11 24H2 (OS Build 26100.3981) is still doing the right thing w.r.t. Shawn's rgy tweak, but the .4061 will be forced on me soon....

I've checked my registry settings on the .4061 PC, and the Taskband.NumThumbnails is still set to the magic value (1).
I've killed all instances of explorer and then relaunched explorer (this is usually sufficient for the rgy tweak to start working).

KB5058411 broke Shawn's "Change Threshold of Taskbar Thumbnails to Show List" registry tweak on Windows 11 24H2 (OS Build 26100.4061),
uninstalling KB5058411 returned the functionality. KB5058411 didn't cause harm on a Win11 24H2 (OS Build 26100.3981) box.