Social icon not working after theme upgrade from 3.8.2 to 4.0.3

Hi, Following the upgrade of the theme from version 3.8.2 to 4.0.3, the social link icon disappeared. When we tried to reprogram any link, the links are clickable, but there is no icon, just an empty circle. However, the custom links are functional beside the embedded social link.   FYI, PHP version was also upgraded from 7 to 8, the server cache accelerator was also flush. Any advice on how to trouble this? The website can be seen here: https://www.ve2cwq.ca/ Thanks in avanced!