lemon-admin/public/vendor/fontawesome/scss/_duotone-icons.scss

// specific duotone icon class definition
// -------------------------

/* Font Awesome uses the Unicode Private Use Area (PUA) to ensure screen
readers do not read off random characters that represent icons */

@each $name, $icon in $fa-icons {
  .fad.#{$fa-css-prefix}-#{$name}::after, .#{$fa-css-prefix}-duotone.#{$fa-css-prefix}-#{$name}::after {
    content: unquote("\"#{ $icon }#{ $icon }\"");
  }
}