And here is the content after I copy from Chrome’s devtools while inspecting the TW result. You can see all the namespaces are gone:
<svg version="1.1" width="121px" viewBox="-0.5 -0.5 121 61">
<defs/>
<g>
<rect x="0" y="0" width="120" height="60" fill="rgb(255, 255, 255)" stroke="rgb(0, 0, 0)" pointer-events="all"/>
<g transform="translate(-0.5 -0.5)">
<switch>
<foreignObject pointer-events="none" width="100%" height="100%" requiredFeatures="http://www.w3.org/TR/SVG11/feature#Extensibility" style="overflow: visible; text-align: left;">
<div style="display: flex; align-items: unsafe center; justify-content: unsafe center; width: 118px; height: 1px; padding-top: 30px; margin-left: 1px;">
<div data-drawio-colors="color: rgb(0, 0, 0); " style="box-sizing: border-box; font-size: 0px; text-align: center;">
<div style="display: inline-block; font-size: 12px; font-family: Helvetica; color: rgb(0, 0, 0); line-height: 1.2; pointer-events: all; white-space: normal; overflow-wrap: normal;">Tiddlywiki</div>
</div>
</div>
</foreignObject>
<text x="60" y="34" fill="rgb(0, 0, 0)" font-family="Helvetica" font-size="12px" text-anchor="middle">Tiddlywiki</text>
</switch>
</g>
</g>
<switch>
<g requiredFeatures="http://www.w3.org/TR/SVG11/feature#Extensibility"/>
<a transform="translate(0,-5)" xlink:href="https://www.diagrams.net/doc/faq/svg-export-text-problems" target="_blank">
<text text-anchor="middle" font-size="10px" x="50%" y="100%">Text is not SVG - cannot display</text>
</a>
</switch>
</svg>