So you can add something like this to your mix custom styles field:
:root { --fa-primary-color: green; --fa-primary-opacity: 1.0; --fa-secondary-color: red; --fa-secondary-opacity: 1.0; }
So it will look like this:
#fontawesome #duotone #tipsandtricks
Woaw ! This solution is radical and closed the problem, thank you very much for this information.