[BUG] Storing with parse-xml-fragment adds unnecessary xmlns prefixes

[lguariento]

Though not specifically a bug, this issue is more like of a nuisance which would be good if addressed.

Describe the bug
When storing a node containing sub-nodes, the latter will get a prefix and a xmlns added, even if the parent node is in the correct xmlns.

Expected behavior
It'd be good if, instead, the sub-nodes had no xmlns or prefixes (if they're supposed to be on the same namespace of the parent of course).

To Reproduce

xquery version "3.1";

declare namespace tei = "http://www.tei-c.org/ns/1.0";

declare variable $base-tei-doc := document {
    <listPerson xmlns="http://www.tei-c.org/ns/1.0">
        <person xml:id="1">
            <persName>
                <surname>Ozzy</surname>
                <forename>Osbourne</forename>
            </persName>
        </person>
    </listPerson>
};

declare variable $note-content-1 := document { <hi>testing1</hi> };
declare variable $note-content-2 := parse-xml-fragment("<hi>testing1</hi>");
declare variable $note-content-3 := document { <hi xmlns='http://www.tei-c.org/ns/1.0'>testing2</hi> };
declare variable $note-content-4 := parse-xml-fragment("<hi xmlns='http://www.tei-c.org/ns/1.0'>testing2</hi>");

let $stored-doc := xmldb:store("/db", "example1.xml", $base-tei-doc)
return
    let $list-person := doc($stored-doc)/tei:listPerson
    
    let $person-record := 
        <person xmlns="http://www.tei-c.org/ns/1.0">
            <persName>
                <surname>Zakk</surname>
                <forename>Wylde</forename>
                <note>{$note-content-1}</note>
                <note>{$note-content-2}</note>
                <note>{$note-content-3}</note>
                <note>{$note-content-4}</note>
            </persName>
        </person>
    
    return
        update insert $person-record into $list-person

This produces /db/example1.xml:

<listPerson xmlns="http://www.tei-c.org/ns/1.0">
    <person xml:id="1">
        <persName>
            <surname>Ozzy</surname>
            <forename>Osbourne</forename>
        </persName>
    </person>
    <person>
        <persName>
            <surname>Zakk</surname>
            <forename>Wylde</forename>
            <note>
                <hi xmlns="">testing1</hi>
            </note>
            <note>
                <hi xmlns="">testing1</hi>
            </note>
            <note>
                <hi>testing2</hi>
            </note>
            <note>
                <tei:hi xmlns:tei="http://www.tei-c.org/ns/1.0">testing2</tei:hi>
            </note>
        </persName>
    </person>
</listPerson>

Context (please always complete the following information)

eXist-6.4.0
openjdk 17.0.15 2025-04-15
OpenJDK Runtime Environment (build 17.0.15+6-Debian-1deb12u1)
OpenJDK 64-Bit Server VM (build 17.0.15+6-Debian-1deb12u1, mixed mode, sharing)
Linux Debian 12.11

Additional context
JAR installation

[dizzzz]

as I see it, testing1 (2x) and the testing2 (the 2nd) are ok. I am in doubt of the 1st testing 2.

for testing1 explicitly an element without a namespace (aka empty namespace) is inserted, so I don't expect the engine derive the namespace in the root element.

however: Inserting a document node into a document is a bit tricky, I'd use then element instead. Please note there is a difference between a document node and an element node. For te consequences we'd need to study the spec.