I think that extreme scaling in either direction will cause problems. At least that's what I observed when this SVG got rendered like this. The setup here is that for mathematical reasons, the circles there have radius 1, so there is a scale factor of over 100 applied to the whole image via its viewBox. As a consequence, the vertical positioning in rsvg is too low, and within a span of text there apparently is no horizontal advancment between glyphs, so they all buch at the same position. Both of this could be either due to font metric getting rounded inappropriately, or due to some transformation not getting applied to said metrics. I managed to work around the issues in later versions by manually scaling the text part, but that's rather annoying. I have librsvg 2.40.13 installed locally, and at least my issue is not solved by that version.