Why CentOS 8 upgrade removes kernel files?

I have ran sudo dnf update -y on CentOS which is few months old. I had this amongst other stuff it was doing:

I am sure its nothing to worry about (right?) but would like to know why is that and is it documented anywhere?

Solution 1:

Reboot and confirm the system comes back up. Restarting is necessary after core libraries like kernel and libc are updated, and a good idea after other updates as well.

Read man dnf.conf regarding the config option installonly_limit. Certain installonlypkgs always install, never upgrade, and so have multiple versions at once. kernel is on this list by default, enables recovery in case of a bad kernel update. Default limit is 3, as too many consumes disk space with obsolete packages.