RemoveUselessUnionReturnDocblockRector

Remove @return union docblock that is broader than a more specific, non-array native return type

 final class SomeClass
 {
-    /**
-     * @return bool|mixed|string
-     */
     public function run(): false|string
     {
     }
 }

Configure your rector.php:

<?php

use Rector\Config\RectorConfig;
use Rector\DeadCode\Rector\ClassMethod\RemoveUselessUnionReturnDocblockRector;

return RectorConfig::configure()
    ->withRules([
        RemoveUselessUnionReturnDocblockRector::class,
    ]);
SETS:  Dead Code