/usr/share/lxqt/graphics/lxqt_logo.png is in lxqt-system-theme 0.12.0-3.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/lxqt/graphics/helix_150.png
/usr/share/lxqt/graphics/helix_150.png