use a function to get the modify fonts dir value

inc/fonts.php

@@ -12,23 +12,24 @@
  * Kick off our customizations to the WP_Font_Library.
  */
 function bootstrap() {
+/**
+ * Get the value of the pantheon_modify_fonts_dir filter.
+ * By default, this should return true (we're filtering).
+ *
+ * @return bool Whether to modify the fonts directory.
+ */
+function pantheon_modify_fonts_dir() {
 	/**
 	 * Modify the fonts directory.
 	 *
 	 * By default, this is set to true, so we can override the default fonts directory from wp-content/fonts to wp-content/uploads/fonts.
 	 *
 	 * Use the filter to set to false and use the default WordPress behavior (committing fonts to your repository and pushing from dev -> test -> live).
 	 *
-	 * @param bool $modify Whether to modify the fonts directory.
+	 * @param bool $modify_fonts_dir Whether to modify the fonts directory.
 	 */
-	define( 'PANTHEON_MODIFY_FONTS_DIR', apply_filters( 'pantheon_modify_fonts_dir', true ) );
-
-	if ( PANTHEON_MODIFY_FONTS_DIR ) {
-		// Use the new font_dir filter added in WordPress 6.5. See https://github.com/WordPress/gutenberg/pull/57697.
-		add_filter( 'font_dir', __NAMESPACE__ . '\\pantheon_font_dir' );
-	}
+	return apply_filters( 'pantheon_modify_fonts_dir', true );
 }
-add_action( 'init', __NAMESPACE__ . '\\bootstrap' );
 
 /**
  * Define a custom font directory for the WP Font Library.