Hi, it may be caused by template that loads old Font Awesome 4.7 and there is conflict. Please make a quick test, switch to Protostar and check again.

We can help but we need more details + screenshot link + site URL etc.

Template name is "Varsita"?

In my Joomla, there is only one template Shaper helix3 version 2.5.8

Helix3 = old template and loads FA 4.7, not FA 5.x.

I asked you about URL with broken icons, please share if you need help.

I haven't used these icons on the site yet, but it turns out that you don't need to update the Font Awesome if your template is not updated to use the new Font Awesome version, yes? will they just be white squares in the SP Pag Builder addon icons? If in the future I want to use new icons, which template should I use?

Based on Helix Ultimate 1.x or upcoming Helix Ultimate 2.0 - both of them support Font Awesome 5.x

but of course also problems with FA 4.7 can be removed in Helix3 template, but you haven't shared any URL yet.

I am very sorry, this is mysterious, but today all the icons that were not visible have appeared and are displayed perfectly. Sorry again and thanks for everything.

Maybe it was browser bad day, nothing more. You're welcome.