In Firefox 119 Fingerprinting protection has been added to Enhanced Tracking Protection in Strict/Custom mode (Custom: Suspected fingerprinters) what affects accessing local fonts. To include user installed fonts, modify this pref on the about:config page:

• about:config => privacy.fingerprintingProtection.overrides => -FontVisibilityBaseSystem,-FontVisibilityLangPack

You can open the about:config page via the location/address bar. On the warning page, click "Accept the Risk and Continue" to open about:config.

• https://support.mozilla.org/en-US/kb/about-config-editor-firefox

Does it still happen if you disable Tracking Protection for the site?

Thanks for those tries. Turning off Tracking Protection was to no avail, see screenshot 2. Assuming I set the fingerprintingprotection overrides correctly (screenshot 1) , neither did that setting (I set it, restarted ffox, then checked it was still set, then checked gmail which is also showing these boxes for some hebrew) Is there maybe some font package for mac that I'm missing? I have the heb. lang keyboard and can type in various heb. fonts but perhaps there's a particular one ffox likes that I dont have?

Does it still happen in Troubleshoot Mode?

You can check in Font Book for font issues like corrupted and duplicate fonts. Note that you should be careful about disabling "Allow pages to choose their own fonts, instead of your selections above" as this will cause issues with iconic fonts used by webpages to display small icons (you may see text labels instead of icons).

You can right-click and select "Inspect" to open the built-in Inspector with this element selected.

• https://firefox-source-docs.mozilla.org/devtools-user/page_inspector/how_to/open_the_inspector/
• https://firefox-source-docs.mozilla.org/devtools-user/page_inspector/how_to/examine_and_edit_html/

You can check in the Rules tab in the right panel in the Inspector what font-family is used for selected text. You can check in the Fonts tab in the right panel in the Inspector what font is actually used because Firefox might be using a different font than specified by the website. If the Fonts tab is hidden, click the down arrow at the right end.

• https://firefox-source-docs.mozilla.org/devtools-user/page_inspector/how_to/edit_fonts/