The core node type definition contains following:

<nodeTypes
    xmlns:rep="internal"
    xmlns:nt="http://www.jcp.org/jcr/nt/1.0"
    xmlns:mix="http://www.jcp.org/jcr/mix/1.0"
    xmlns:mgnl="http://www.magnolia.info/jcr/mgnl"
    xmlns:jcr="http://www.jcp.org/jcr/1.0">

Some of the URIs seems obsolete/invalid.
This issue became more visible with MAGNOLIA-6683 which new export command doesn't go trough the magical filtering via info.magnolia.importexport.filters.MetadataUuidFilter#removeUnwantedNamespaces/validNs (as you can see, the filter name is completely unrelated) so the export now contains all the namespaces:

<sv:node xmlns:sv="http://www.jcp.org/jcr/sv/1.0" xmlns:rep="internal" xmlns:mix="http://www.jcp.org/jcr/mix/1.0" xmlns:jcr="http://www.jcp.org/jcr/1.0" xmlns:jcrfn="http://www.jcp.org/jcr/xpath-functions/1.0" xmlns:fn_old="http://www.w3.org/2004/10/xpath-functions" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:fn="http://www.w3.org/2005/xpath-functions" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:mgnl="http://www.magnolia.info/jcr/mgnl" xmlns:nt="http://www.jcp.org/jcr/nt/1.0" sv:name="travel">

Explanation about huge amount of namespaces when exporting might be find here MAGNOLIA-2756 although the solution there seems not correct as such filtering should not be hardcoded only by prefixes.
We should validate if the URIs are still valid and if should be still filtered out.

As a side note, new YAML bootstrap doesn't export any namespaces so there's not such problem.