Index: src/wp-admin/includes/class-wp-site-health.php
===================================================================
--- src/wp-admin/includes/class-wp-site-health.php	(revision 45176)
+++ src/wp-admin/includes/class-wp-site-health.php	(working copy)
@@ -468,11 +468,6 @@
 			$allowed_theme_count++;
 		}
 
-		// If there's a default theme installed, we count that as allowed as well.
-		if ( $has_default_theme ) {
-			$allowed_theme_count++;
-		}
-
 		if ( $themes_total > $allowed_theme_count ) {
 			$has_unused_themes = true;
 			$themes_inactive   = ( $themes_total - $allowed_theme_count );