KDE - kf5-config --version give warning when use in root terminal

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Hello.
I have a script called by /etc/bash.bashrc.local which is used to set env variables for every user ( including root ).
When I open a terminal in super user mode I got this warning before the prompt.
I got the same warning when I type the same command from command line in a terminal in super user mode :

# kf5-config --version
QStandardPaths: XDG_RUNTIME_DIR not set, defaulting to '/tmp/runtime-root'
QStandardPaths: XDG_RUNTIME_DIR not set, defaulting to '/tmp/runtime-root'
QStandardPaths: XDG_RUNTIME_DIR not set, defaulting to '/tmp/runtime-root'
Qt: 5.6.2
KDE Frameworks: 5.32.0
kf5-config: 1.0
#

Any help is welcome