Issue report (17/8/2021):
There is an issue with the FontAwesome plugin and Firefox v91 on Ubuntu 20.04 where the proper font is not displayed but only a placeholder image showing the character code as in F674 for example. The appropriate fonts are installed and the same page worked in previous versions of Firefox while the page works in browsers written in Chromium. I am investigating why this happens but I don't believe this is a bug with FontAwesome but an issue within Firefox.
I am with Firefox v91 on Ubuntu 18.04, and here it appears to work. I'll test it on 20.04 tomorrow. This sometimes happens if you disable loading of remote fonts (options in uBlock Origin and other extensions), or from about:config. --Petko August 17, 2021, at 07:58 PM
Working in Firefox v91 on Ubuntu 20.04 as well -- I'd look for some changes you made recently, notably something that changed the
$FarmPubDirUrl variable. Also, if you have multiple domains with a common (shared) "pub" directory, they probably need to all be on HTTPS protocols. --Petko August 18, 2021, at 06:53 PM