>>> These are the packages that would be unmerged:

 sys-kernel/gentoo-sources
    selected: 4.19.72
   protected: none
     omitted: 5.4.72

It's going to remove an old version and leave a newer version.  If you really want the old one kept, you should explicitly add it to your world file.  (check "emerge -n", don't actually edit the world file)

 sys-kernel/gentoo-sources
    selected: 5.4.66
   protected: none
     omitted: 5.4.72

Same as above, and no, I don't know why it didn't combine these into a single entry with two selected and one omitted.

I understand now that you've checked this list for me.  That is really helpful.  Thank you.

 app-editors/nano
    selected: 4.2
   protected: none
     omitted: none

This seems a bit odd, unless you have a different app-editor package installed.  Virutal/editor is there so you always have at least one editor installed.  If you do have another editor installed, then this is OK.

--depclean just won my heart!  :-)