树莓派4B Ubuntu23.04环境下TigerVNC启动异常求助

各位大佬，我现在在树莓派4B的Ubuntu 23.04系统里配置TigerVNC，碰到了个搞不懂的问题，想请教下大家。

我跟着教程一步步配置到测试环节，输入命令 vncserver 后，得到了如下输出：

New Xtigervnc server 'KG7JE-Ham:1 (steve)' on port 5901 for display :1.
Use xtigervncviewer -SecurityTypes VncAuth -passwd /tmp/tigervnc.IZRuvV/passwd :1 to connect to the VNC server.
--- tail /home/steve/.vnc/KG7JE-Ham:1.log ---
Session startup via '/home/steve/.vnc/xstartup' cleanly exited too early (< 3 seconds)!
Maybe try something simple first, e.g.,
tigervncserver -xstartup /usr/bin/xterm
The X session cleanly exited!
Killing Xtigervnc process ID 576114... success!

看到提示后我试了命令 tigervncserver -xstartup /usr/bin/xterm，这次的输出看起来没问题：

New Xtigervnc server 'KG7JE-Ham:1 (steve)' on port 5901 for display :1.
Use xtigervncviewer -SecurityTypes VncAuth -passwd /tmp/tigervnc.aBtKL_/passwd :1 to connect to the VNC server.

而且我在 /tmp/ 目录里也能看到对应的锁文件，说明这个方式是可以正常运行的。

我查看了 ./.vnc/*.log 的完整内容，里面有这些关键的错误信息：

_XSERVTransmkdir: Owner of /tmp/.X11-unix should be set to root
Xvnc TigerVNC 1.12.0 - built 2023-01-06 16:01
Copyright (C) 1999-2021 TigerVNC Team and many others (see README.rst)
Underlying X server release 12101006, X.Org
Thu Jul 6 13:38:17 2023
vncext: VNC extension running!
vncext: Listening for VNC connections on local interface(s), port 5901
vncext: created VNC server for screen 0
3NI3X0 New Xtigervnc server 'KG7JE-Ham:1 (steve)' on port 5901 for display :1.
3NI3X0 Use xtigervncviewer -SecurityTypes VncAuth -passwd /tmp/tigervnc.OPtlxa/passwd :1 to connect to the VNC server.
/usr/bin/startxfce4: X server already running on display :1
Thu Jul 6 13:38:18 2023
ComparingUpdateTracker: 0 pixels in / 0 pixels out
ComparingUpdateTracker: (1:nan ratio)
xrdb: Connection reset by peer
xrdb: Can't open display ':1'
xfce4-session: Cannot open display: .
Type 'xfce4-session --help' for usage.

现在我想弄明白，为什么直接运行 vncserver 会启动失败，而指定xterm作为启动程序就能正常工作？有没有办法修复默认的xstartup配置，让vncserver能直接正常启动呢？

备注：内容来源于stack exchange，提问作者Steve Butler