That's odd, MathJax does *not* render the math as images (unless you configure t...

That's odd, MathJax does not render the math as images (unless you configure the output format to be SVG, but even that is not the default). Do you have a memory of (or can retrace) how you ended up with that unusual configuration?

(MathJax's output formats, namely HTML+CSS, SVG, MathML — see https://mathjax.github.io/MathJax-demos-web or https://docs.mathjax.org/en/latest/output/ — are strictly a superset of KaTeX's output formats, namely HTML+CSS and MathML: https://katex.org/docs/options.html )