Maps the old-style Font Awesome prefixes to the new Font Awesome 6.x format.

src/Plugin/Field/FieldFormatter/FontAwesomeIconFormatter.php

@@ -183,7 +183,7 @@ class FontAwesomeIconFormatter extends FormatterBase implements ContainerFactory
         '#tag' => $configurationSettings->get('tag'),
         '#iconset' => $iconset,
         '#name' => 'fa-' . $item->get('icon_name')->getValue(),
-        '#style' => $item->get('style')->getValue(),
+        '#style' => $this->mapStylePrefix($item->get('style')->getValue()),
         '#settings' => implode(' ', array_filter($iconSettings)),
         '#transforms' => implode(' ', $iconTransforms),
         '#mask' => $iconMask,
@@ -203,4 +203,29 @@ class FontAwesomeIconFormatter extends FormatterBase implements ContainerFactory
     ];
   }
 
+  /**
+   * Converts old Font Awesome style prefixes to the 6.x format.
+   *
+   * @param string $style
+   *   The style value from the database.
+   *
+   * @return string
+   *   The corrected style value.
+   */
+  private function mapStylePrefix(string $style): string {
+    if (empty($style)) {
+      return 'fa-solid';
+    }
+
+    $style_mapping = [
+      'fa-fas' => 'fa-solid',
+      'fa-far' => 'fa-regular',
+      'fa-fab' => 'fa-brands',
+      'fa-fal' => 'fa-light',
+      'fa-fad' => 'fa-duotone',
+      'fa-fat' => 'fa-thin',
+    ];
+    return $style_mapping[$style] ?? $style;
+  }
+
 }