PROBLEM:
I had installed Joomla 6 and the Artolio template package using your Quickstart Package (Joomla 6), updated all to the newest versions and then installed SP Page Builder and updated that along with the Helix Framework. I had also installed Akeeba Admin Tools to protect the website. On the Akeeba Admin Tools control panel some of the icons (on buttons) which are derived from FontAwesome are missing. This seems to be an issue with the Quickstart Package because I deleted that original website and reinstalled Joomla 6 from the Joomla website then installed SP Page Builder standalone as well as the Artolio template standalone. No problems with FontAwesome icons or the Akeeba Admin Tools were detected, but this caused me to lose the demo data shipped with the QuickStart package which is essential to me. I contacted Akeeba and he said that he simply uses Font Awesome icons in the control panel and that the problem is which version of Font Awesome is loaded in the backend. I tried the "Do Not load Font Awesome" in the Artolio template options, purging the cache (both Joomla and browser), still the same result on several browsers, some icons are missing.
SOLUTION:
It looks like the Helix Ultimate Framework Joomla System Plugin which is a part of the JoomShaper diaspora, which was supplied in the Quickstart Joomla package of the Artfolio template is an old version of 2.2.1 which had FontAwesome font files as well as the fontawesome css file included in the assets directory, this was an old version (4.7) of FontAwesome where the icons used by the Akeeba Admin Tools control panel were not available. In the new version (2.2.4) of this Helix Ultimate Framework plugin these FontAwesome files are no longer included at all, but because Joomla performs upgrades by not removing old files/folders (even if you installed a newer version of the Helix Ultimate Framework) but overwriting only the updated files, it would not remove the old FontAwesome files, these files (.min.css etc) then for some reason were loaded in the backend, so some FontAwesome (newer) were loaded from the Atum administrator template and some were loaded from the Helix Ultimate Framework plugin.
WHAT TO DO:
Uninstall the Helix Ultimate Framework system plugin and install the new version which can be downloaded from the JoomShaper site in the Helix Ultimate template download area. Then enable the plugin, problem is gone. All Akeeba Admin Tools icons load fine. This seems to be a problem with a mispackaged QuickStart Artolio template package.