xsettings.xml does not pass xmllint validation.

The XML declaration is allowed only at the start of the file. But xsettings.xml has the XML declaration in line 6, after a comment.

xmllint /etc/xdg/xfce4/xfconf/xfce-perchannel-xml/xsettings.xml 
/etc/xdg/xfce4/xfconf/xfce-perchannel-xml/xsettings.xml:6: parser error : XML declaration allowed only at the start of the document
<?xml version="1.0" encoding="UTF-8"?>
     ^

To fix this, the XML declaration must be moved to line 1.

diff -Naur xfce4-settings-4.18.1.orig/xfsettingsd/xsettings.xml xfce4-settings-4.18.1/xfsettingsd/xsettings.xml
--- xfce4-settings-4.18.1.orig/xfsettingsd/xsettings.xml	2022-12-30 06:42:15.977900072 -0600
+++ xfce4-settings-4.18.1/xfsettingsd/xsettings.xml	2022-12-30 06:43:21.467076127 -0600
@@ -1,9 +1,9 @@
+<?xml version="1.0" encoding="UTF-8"?>
 <!--
   Default values for the X settings registry as described in
   http://www.freedesktop.org/wiki/Specifications/XSettingsRegistry
 -->
 
-<?xml version="1.0" encoding="UTF-8"?>
 <channel name="xsettings" version="1.0">
   <property name="Net" type="empty">
     <property name="ThemeName" type="empty"/>

Once applied, xsettings.xml validates properly.