I-Firefox Isithangami Sokwesekwa

Recently Firefox (both regular and dev edition) started showing monospace fonts in SF Mono Heavy variant. I use macOS 11.4 and Firefox Developer 90.0b6 but it happens with Firefox 89.0 as well, even in Troubleshooting Mode.

Below is a screenshot of a GitHub page. The same page rendered in Safari or Chrome on the same device show normal variant of SF Mono. Notice that the code on the page is rendered in heavy weight.

Running inspector mode shows that Firefox selects SF Mono Heavy even though regular variant is clearly present in the system.

I have tried disabling hardware acceleration and webgl. Are there any other ways to troubleshoot and fix the bug?

I am using an offline web page as my default firefox home page and all was going well until I enabled sync. Now when I boot up firefox two things happen. It changes the address for my home page file to a folder NOT on this computer (the desk top) and won't retain the address I need for that folder.

I have just tried editing the bookmark for page. At the moment it seems to be working but I think sync is causing this issue and wonder if there is a fix for it?

Thank you.

Image

Today, right-click menu options began appearing invisible. There was no issue yesterday and no changes were made to anything since then. The options can still be clicked on and work, but I cannot see the text. Right click menus continue to work normally everywhere outside of Firefox.