Symfony version(s) affected: 5.2.0-RC1 (PHP 7.4.11, MySQL 8.0.22)

Description
There is something strange going on with Ulid since upgrading to RC1. I was playing with the new Ulid doctrine data type on the beta and all was working correctly with new entities being created with id fields that looked like Ulid.

Then I think around the time I updated to RC1 I tried persisting a new entity that had an association with an existing entity with a ulid primary key and I got a foreign key constraint error. I don't have the exact error message now (I will try to work back through the steps to reproduce if I can). However it seemed to be trying to set the foreign key value for my new association to a value that looked like a uuid (longer than a ulid and with hyphens) and the foreign key constraint rightly failed because there was no corresponding association with a matching primary key (because the existing entity had a uuid for primary key).

This was just in a local dev database so I just dropped the schema and rebuilt it with migrations and walked through the scenario again and this time I got no error but I checked the database and all my ulid columns are now populated with uuid.

Here is an example entity:

<?php

declare(strict_types=1);

namespace App\Domain\Entity;

use Doctrine\ORM\Mapping as ORM;
use Symfony\Bridge\Doctrine\IdGenerator\UlidGenerator;
use Symfony\Component\Uid\Ulid;

/**
 * @ORM\Entity
 */
class Organisation
{

    /**
     * @ORM\Id
     * @ORM\Column(type="ulid", unique=true)
     * @ORM\GeneratedValue(strategy="CUSTOM")
     * @ORM\CustomIdGenerator(class=UlidGenerator::class)
     * @var Ulid|null
     */
    public ?Ulid $ulid = null;

    /**
     * @ORM\Column(type="string", length=140)
     * @var string|null
     */
    public ?string $name = null;
}

The migration looks like this:

<?php

declare(strict_types=1);

namespace DoctrineMigrations;

use Doctrine\DBAL\Schema\Schema;
use Doctrine\Migrations\AbstractMigration;

/**
 * Auto-generated Migration: Please modify to your needs!
 */
final class Version20201026201204 extends AbstractMigration
{
    public function getDescription() : string
    {
        return '';
    }

    public function up(Schema $schema) : void
    {
        // this up() migration is auto-generated, please modify it to your needs
        $this->addSql('CREATE TABLE organisation (ulid CHAR(36) NOT NULL COMMENT \'(DC2Type:ulid)\', name VARCHAR(140) NOT NULL, PRIMARY KEY(ulid)) DEFAULT CHARACTER SET utf8mb4 COLLATE `utf8mb4_unicode_ci` ENGINE = InnoDB');
    }

    public function down(Schema $schema) : void
    {
        // this down() migration is auto-generated, please modify it to your needs
        $this->addSql('DROP TABLE organisation');
    }
}

When a new entity is persisted with a name I get this in the db:

ulid,name
0175dd53-f32a-b9d5-9841-b4a0bec7aaf0,Acme Ltd.

However in code when I get the entity out the repository and run $organisation->getUlid()->__toString() on the same entity I get a ulid back 01EQEN7WSAQ7ASGGDMM2ZCFAQG

How to reproduce
Create an entity with a Ulid column
Persist the entity
Look in the database
The column contains a Uuid

Expected behaviour
The column should contain a Ulid in the db