LXQt 2.0.0 using qt6 is in Tumbleweed now, but a few libraries are recommended
by upstream to have co-installable qt5 and qt6 versions for integration. These
include lxqt-build-tools, lxqt-qtplugin, libfm-qt, and libqtxdg.

The qt5 versions of lxqt-qtplugin and libfm-qt are missing and not installable
in Tumbleweed. These are the 1.4.x versions of these libraries. See the release
notes here: https://lxqt-project.org/release/2024/04/15/release-lxqt-2-0-0/
section "Note for Distros."

Result: qt5 apps running within LXQt 2.0.0 on Tumbleweed are not integrated
with theming and the LXQt file dialog.

Steps to reproduce:
1. Install and run LXQt 2.0.x on Tumbleweed
2. Set Appearance settings according to your preferences, and check the results
in any qt6 app
3. Install and open any qt5 app, such as VLC

Actual results:
qt5 apps do not follow any theme settings set by the LXQt appearance settings,
regarding qt widget style, fonts, etc. qt6 apps do follow theming.
qt5 apps use the fallback qt file dialog, while qt6 apps use LXQt file dialog.

Expected results:
qt5 apps follow the same style and font settings as qt6 apps, as set in
Appearance settings. 
qt5 and qt6 apps all use the LXQt file dialog.

openSUSE Tumbleweed 2024 early June release (I found the problem Monday, June
2, at the then-current release, when LXQt 2.0 first landed in Tumbleweed) on
Asus Vivobook M513I

First bug report here, please be gentle if I've missed something essential.