Your package breaks/replaces lxqt-panel (<< 1.4), however the latest
lxqt-panel in sid is 1.3.0-1. This means that those packages cannot
be co-installed atm, which is making lxqt-core uninstallable now.
If the reason for this breaks/replaces was to take over some files
from lxqt-panel, then a new version of lxqt-panel should be uploaded
with a high enough version and without those files.
In a fresh sid chroot:
root@andromeda:/# apt install lxqt-core
Unsatisfied dependencies:
lxqt-menu-data : Breaks: lxqt-panel (< 1.4) but 1.3.0-1+b1 is to be installed