first launch of vitas-icon-theme, specially designed for use in high resolution monitors, its update depends on your acceptance.
for greater integration it is recommended to install the classic theme "Zafiro-Icons"
download the latest version from "Files", or from this link
you will get a compressed file in ".tar.gz", unzip in your HOME in the folder
If it does not exist, create it.,
in the KDE desktop environment the path is
with root you can unzip in