PropertyDeferToDeferrableProviderToRector

Change deprecated $defer = true; to Illuminate\Contracts\Support\DeferrableProvider interface

 use Illuminate\Support\ServiceProvider;
+use Illuminate\Contracts\Support\DeferrableProvider;

-final class SomeServiceProvider extends ServiceProvider
+final class SomeServiceProvider extends ServiceProvider implements DeferrableProvider
 {
-    /**
-     * @var bool
-     */
-    protected $defer = true;
 }

Configure your rector.php:

<?php

use RectorLaravel\Rector\Class_\PropertyDeferToDeferrableProviderToRector;
use Rector\Config\RectorConfig;

return RectorConfig::configure()
    ->withRules([
        PropertyDeferToDeferrableProviderToRector::class,
    ]);