Missing font on mathjax output

[agjohnson]

On tests from sphinx 1.8 to Sphinx 4.1, the paragraph link text is showing placeholder font.

Test set up: firefox 88 on arch linux, html5 output.

Sphinx 1.8:

Sphinx 4.1:

This doesn't look to be an issue with the previous release:

[agjohnson]

Probably not a missing font necessarily. It looks like the actual text of the link changes between sphinx_rtd_theme 0.5.2 and what is in master.

[Blendify]

I found the issue and creating a PR: #1191