bug#51478: icecat 91 can't display chinese font in many web page

[ison]

I'm not entirely sure if this is related, but after upgrading to 91
icecat would no longer use fonts from anywhere but my home directories
(~/.fonts or ~/.local/share/fonts).
And changing the whitelist to /gnu/store doesn't fix it.

What's strange is that the fonts are still listed in the icecat font
settings, but it won't use them. Even if I uncheck the box to allow
pages to choose their own fonts.

For example my LiberationSans font stopped working. But if I copy it (or
symlink it) to my ~/.fonts then it works.
NOTE: I test it by changing security.sandbox.content.read_path_whitelist
in about:config to "/gnu/store", closing icecat, running fc-cache -fv
(both as root and normal user), then opening icecat again. And it still
only uses LiberationSans if it gets copied to my home.