See this recent thread about font issues on Mac: *[/questions/1431502] Words are unreadable

This is a font issue on Mac and we have seem quite a few such reports over time. *https://support.mozilla.org/en-US/search/?product=firefox&w=2&q=mac%20weird%20font See also this bug report. *[https://bugzilla.mozilla.org/show_bug.cgi?id=1803406 1803406] - [macOS] Text rendering issues when users have multiple fonts which internally use the same name, and the OS chooses differently among them for different Firefox processes (<i>please do not comment in bug reports<br>https://bugzilla.mozilla.org/page.cgi?id=etiquette.html</i>) ---- On the Firefox Home page in the second screenshot you should be able to right-click this weird text and open the Inspector. There you can open the Fonts tab in the right panel to see what font Firefox is using. 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 <b>Rules</b> tab in the right panel in the Inspector what font-family is used for selected text. You can check in the <b>Fonts</b> 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/

Workarounds include: * Uninstall old or unused fonts. * Identify the garbled font with devtools inspector (Cmd+Opt+C) and uninstall it. * Go to [https://support.mozilla.org/en-US/kb/about-config-editor-firefox about:config] and change '''gfx.e10s.font-list.shared''' and '''gfx.font-list-omt.enabled''' to '''false''' then restart the browser.