It seems that the last gnome-shell update in Focal regressed an extension that then had to be fixed in a separate SRU. I’m told that extensions can use any part of gnome-shell, so any changes to gnome-shell can break compatibility with extensions. To continue being able to update gnome-shell, it looks more testing will be needed every time to avoid the same thing happening again.
I posted about this in the discussion about the GNOME microrelease exception and have updated the SRU documentation for the exception.
If those interested in getting gnome-shell updates in stable releases could help with the necessary testing when the time comes please, this will help these updates land.