Concerned to realise some svg elements weren’t rendering on spotthehall in chrome/brave/vivaldi type browsers, so did a little digging and tracked it down to the way I was creating the svgs.

Those made in Gravit didn’t render and those from Inkscape did. Having opened them in a text editor, it seems to be down to the inclusion of: xmlns:svg="www.w3.org/2000/svg"

Inkscape:

xmlns:xlink="www.w3.org/1999/xlin…"
xmlns="www.w3.org/2000/svg"
xmlns:svg="www.w3.org/2000/svg">

Gravit:

xmlns:xlink="www.w3.org/1999/xlin…"
xmlns="www.w3.org/2000/svg"