Hi there!
Sorry for your issue.
Please use the following code in your custom CSS:
.sp-megamenu-parent .sp-dropdown .sp-dropdown-items .sp-has-child>a:after {
font-family: 'Font Awesome 5 Free';
font-weight:600;
}
Note: Path towards custom CSS(Joomla 4): System>Site Templates Styles> Click on your current default template name then choose Template Options. Then find custom CSS within the custom code.
https://prnt.sc/5mBuSRh907N3
https://prnt.sc/ooiq-lkMEXr_
https://prnt.sc/nunlX-f5AhK1
Moreover, Our Helix3 based templates support PHP 7.4 maximum. Hopefully next week we will come with PHP 8.0 support.
Best Regards