I just installed Ubuntu server and XFCE4, however the desktop is completely different than any other xfce I have installed, with a gnome-like launcher and both Ubuntu and Debian screen backgrounds, as well as no start menu or panel. But Thunar is there.
I understand that there were a lot of changes to Xubuntu 19.04, but nothing I read about said anything about this. So take a look at my screenshot of a fresh install of Ubuntu Server + xfce4 (and a few utilities).
Is this expected (nevermind the checkerboard pattern thing, sometimes my graphics card does that).
Additional notes: This happened on two installs back-to-back. Also, the mouse tracking and stuff are really slow, although that could be due to having five monitors spread across three video cards, but I don't remember this being an issue in the past)
You didn't install the xubuntu desktop, instead xfce4
https://packages.ubuntu.com/disco/xfce4
which does include
desktop-base
https://packages.ubuntu.com/disco/desktop-base described aswhich suggests
gnome
https://packages.ubuntu.com/disco/gnomeso I'd check your logs and see what you actually installed.
You may have accepted the suggested/recommended packages pulling in
gnome
because of your provided command, esp. if you 'y' or included a-y
to accept recommends; possibly you should consider--no-install-recommends