Inside text elements both in HTML and SVG white-space is significant and introduces differences in how things are rendered. By default in general all white-space is collapsed into one space and then this is rendered, adding additional text content.

I observed this while working with SVG which can have content like:

<text><tspan>foo</tspan><tspan>bar</tspan></text>

After pretty-printing it with minidom, and white-space collapsing, the following is what is input to SVG rendering:

<text> <tspan>foo</tspan> <tspan>bar</tspan> </text>

And space between "foo" and "bar" is now visible and while before it was one word to the user, now it is shown as two.

Related issue: https://github.com/mozman/svgwrite/issues/58

I think pretty-printing not add whitespace inside text elements.