Comment # 12 on bug 970653 from Cameron Poe

I have the same issue :(

Unfortunately this is a bug!!!
I have changed desktop themes to all installed and none of them changed those
icons!!!

It happened 1st of March after openSUSE 42.1 framework update as Donald Curtis
said.

Not only those shutdown, reboot and log-out icons have been changed, but for
example application icons VLC, SMPlayer, Ktorrent and mime types icons for
pictures and videos have been changed to breeze as well!!! :(

Back then I managed to changed them back to oxygen by deleting breeze and
hicolor catalogs in /usr/share/icons and it went back to normal, but now it
don't seem to work for applications icons. For example I had to reinstall VLC
after deleting breeze icons to see oxygen VLC icon again. But still shutdown,
reboot and log-out icons in KDE menu are breeze and all breeze is terrible!!!
:(

Funny thing is that you cannot uninstall breeze themes because it will
uninstall the whole Plasma :o

Comment # 11 on bug 970653 from Raymond Wooninck

(In reply to Donald Curtis from comment #10)
> A suggestion for a panel discussion at the openSUSE Conference in June:
> "To Breeze or not to Breeze ��� that is the question; whether 'tis nobler in
> the mind to suffer the outrageous fortune of Oxygen, or to take arms against
> a sea of Themes, and by opposing end them?"

Donald, Whatever that panel would decide or indicate, it is the wrong place to
discuss this.  openSUSE is not the one who maintains Plasma, nor the Oxygen and
Breeze themes. 

As I indicated before already, the Oxygen desktop theme does not provide icons
for the plasmoids and the systray. Therefore the fallback icons are being used,
which for Plasma5 is the Breeze theme. 

You are free to select any other desktop theme and maybe those would provide a
corresponding icon theme. Alternative you could raise a bug or feature request
on http://bugs.kde.org and request for the Oxygen theme to have corresponding
desktop theme icons.