In Laravel there is a change for DB:SEED

If you migrated to Laravel 8, you have to add a namespace to the seeders class:

<?php

namespace Database\Seeders;

...

Next, in your composer.json file, remove classmap block from the autoload section and add the new namespaced class directory mappings:

"autoload": {
    "psr-4": {
        "App\\": "app/",
        "Database\\Seeders\\": "database/seeds/"
    }
},

An finally, do a composer dump-autoload.