Laravel test returns 404 - laravel

Question

I'm trying to run some tests but it is returning 404 after the first run. Sometimes it runs normally, but 90% of the time, it returns me a 404 response.
Pstoman request works 100% of the time.
First time running (the failure here is from another test):
Next times (now I'm getting the 404):
Here is my phpunit.xml
<?xml version="1.0" encoding="UTF-8"?>
<phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:noNamespaceSchemaLocation="./vendor/phpunit/phpunit/phpunit.xsd"
bootstrap="vendor/autoload.php"
colors="true"
>
<testsuites>
<testsuite name="Unit">
<directory suffix="Test.php">./tests/Unit</directory>
</testsuite>
<testsuite name="Feature">
<directory suffix="Test.php">./tests/Feature</directory>
</testsuite>
</testsuites>
<coverage processUncoveredFiles="true">
<include>
<directory suffix=".php">./app</directory>
</include>
</coverage>
<php>
<server name="APP_ENV" value="testing"/>
<server name="APP_URL" value="http://localhost"/>
<server name="BCRYPT_ROUNDS" value="4"/>
<server name="CACHE_DRIVER" value="array"/>
<server name="DB_CONNECTION" value="sqlite"/>
<server name="DB_DATABASE" value=":memory:"/>
<server name="MAIL_MAILER" value="array"/>
<server name="QUEUE_CONNECTION" value="sync"/>
<server name="SESSION_DRIVER" value="array"/>
<server name="TELESCOPE_ENABLED" value="false"/>
</php>
</phpunit>
The test:
public function verify_username_should_return_id_when_existing_document()
{
$this->seed(UserTypeSeeder::class);
$user = User::factory()->create();
$response = $this->withHeaders([
'user_type' => $user->type->id,
])->postJson("api/auth/username", [
"username" => $user->document
]);
$response->assertOk()
->assertJson(["id" => 1]);
}

Answer 1

I found that for some reason if I change the $this->withHeaders(['user_type' => $user->type->id,]) to $this->withHeader("user_type", $user->type->id) it works but it doesn't make sense to me