Filter query vars in slugs

Remove the query vars that were part of the matched query before slugs.
Keep the new query vars with the matched query found by slugs.

modules/slugs/src/slugs-class-slugs.php

@@ -302,17 +302,24 @@ public function query_vars( $query_vars ) {
             }
 
             if ( isset( $wp->matched_rule ) && isset( $query ) && isset( $matches ) ) {
+                // Store the query vars before update with slugs
+                parse_str( $wp->matched_query, $query_vars_before_slugs_match );
                 // Trim the query of everything up to the '?'.
                 $query = preg_replace( "!^.+\?!", '', $query );
                 // Substitute the substring matches into the query.
                 $query             = addslashes( WP_MatchesMapRegex::apply( $query, $matches ) );
                 $wp->matched_query = $query;
                 // Parse the query.
                 parse_str( $query, $perma_query_vars );
-                // If we're processing a 404 request, clear the error var
-                // since we found something.
+                // If we're processing a 404 request, clear the error var since we found something.
                 unset( $_GET['error'] );
                 unset( $error );
+                // Remove all query vars previously set in the matched query, as they may not be consistent with the slugs request.
+                $to_remove  = array_keys( $query_vars_before_slugs_match );
+                $to_keep    = array_keys( $perma_query_vars );
+                $query_vars = array_filter( $query_vars, function ( $item ) use ( $to_remove, $to_keep ) {
+                    return ! in_array( $item, $to_remove ) || in_array( $item, $to_keep );
+                } );
             }
 
             // If req_uri is empty or if it is a request for ourself, unset error.
@@ -326,8 +333,7 @@ public function query_vars( $query_vars ) {
             }
         }
 
-        // TODO check this call, looks bug-prone
-        return count( array_diff( $query_vars, $wp->public_query_vars ) ) > 0 ? $query_vars : $wp->public_query_vars;
+        return $query_vars;
     }
 
     /**