Follow-up on CF 2021 update 15: understanding, solving packages unexpectedly removed
In this post, I discuss this issue, those options for adding them back, and I also share how I'd found the underlying root cause of the problem: the update has a mistaken internal indication that these packages were updated in this update, when they were not. I'm hoping that Adobe may soon be fixing the problem by creating a new update file, to at least benefit those doing this update going forward. I'll share also the bug report for that (and another on a related matter, about installing multiple packages via cfpm).
TLDR
If you just want to "solve the problem" caused in applying this update 15, simply go into the CF Admin and its "Package Manager" page, go to its "Available Packages" section, and click each of those to install them. (Couldn't you also click the "Install All" button offered there? Yes, but there are reasons to be careful about that. Couldn't you use the cfpm tool? Again, yes. I will address both these points and more, below.)