This isn't solved as the topic suggests. Using another browser is a work-around, not a solution / fix. And unfortunately some people such as myself, using Firefox or Chrome, even on different workstations / laptops it is still is displaying an unreadable font. I have multiple unraidOS systems and each of them was fine before 6.9.x. So the new version is where the issue resides.
Ubuntu 20.04 - Google Chrome or Firefox have issue
LInux Mint - Google Chrome or Firefox have issue
WIndows 10 - Google Chrome has issue | Firefox works fine
Mac OS - Firefox works Fine | Google Chrome viewable, but can still notice imperfect font when changing zoom