Somewhat a duplicate of #22281, but we should be doing something for users to rebuild the font cache if there is a failure in findfont. findfont: Font family ['cmsy10'] not found. Falling back to ...
Starting with 3.5.0, figures exported as SVG without font embedded in the file (i.e. “svg.fonttype” set to “none”) use the font CSS shorthand property. The problem is that the font-family generic name ...