[INDD 2020 and 2021] Document fonts folder does not work with fonts for placed SVGs
Provide a font file with the Document fonts folder for a placed SVG graphic where the font is not embedded.
RESULT: InDesign will not use the font for rendering text with the placed SVG graphic.
ALSO: Even if the font is installed for ALL USERS in the system on Windows 10 InDesign will not package the font that is needed with the placed SVG graphic.
One cannot be sure what fonts are needed with placed SVG graphics. When InDesign documents are saved, closed and re-opened, Preflight and Type > Find Fonts… will not show them.
The only check you can do:
Export the document to IDML. Open the IDML file as document.
Then Preflight will show a needed font inside a placed SVG graphic and Preflight could flag it if it is missing.
Well: The missing font installed in the Documents fonts folder could even block InDesign to access the same font that is installed for all users with:
To solve the issue you have to do THREE things:
 Move the needed font for the placed SVG file out of the Document fonts folder
 Install the font for ALL USERS
 Quit and restart InDesign, only then open the document again. Otherwise you get a situation where the font could show as missing if it used in a text frame elsewhere in the document like [Lemon], but is rendered correctly in a text frame. And still rendered substituted with Arial in the placed SVG graphic. See screenshot: "NoAccessToFont-EvenWhenInstalledFor-AllUsers.JPG" in my test files one can download from my Dropbox account:
( ACP )