Ticket #46900: 46900.3.diff

src/wp-admin/includes/class-wp-site-health.php

@@ -464 +464 @@
                 // If this is a child theme, increase the allowed theme count by one, to account for the parent.
                 if ( $active_theme->parent() ) {
                         $allowed_theme_count++;
+
+                        if ( $active_theme->get_template() === WP_DEFAULT_THEME ) {
+                                $using_default_theme = true;
+                        }
                 }
 
-                // If there's a default theme installed, we count that as allowed as well.
-                if ( $has_default_theme ) {
+                // If there's a default theme installed and not in use, we count that as allowed as well.
+                if ( $has_default_theme && ! $using_default_theme ) {
                         $allowed_theme_count++;
                 }