KDE theme change leads to icons change, won't revert back

[local10 <local10@tutanota.com>]

Hi,

Was playing with/changing KDE desktop themes thinking maybe there was another theme I would like better, tried the Oxygen and Air themes, decided to revert to the original one I had (Breeze) but some icons in the QuickLaunch panel changed and won't revert to what they had always been in the Breeze theme. For example, VLC used to have a white-and-orange cone on the transparent background icon but now it's a black-and-orange cone on black background icon, JuK used to have a green "Note" icon but now it's a black circle with orange center.

Some icons in the QuickLaunch panel I can change, some can't:
    Can change: Firefox, Dolphin, Konqueror, etc,
    Can't change: Konsole, Juk, Vlc, KCalc, Kwrite, etc,

Any ideas? Thanks

# echo "This is a Debian 10 Buster PC" && uname -a
This is a Debian 10 Buster PC
Linux tst4 4.19.0-13-amd64 #1 SMP Debian 4.19.160-2 (2020-11-28) x86_64 GNU/Linux

# aptitude show kde-standard
Package: kde-standard                   
Version: 5:102