Why does the `for` method not work for the belongTo relationship?

Question

I want to test the memberOfTeam relationship from the User model using factories. According to the Laravel document, I should use for, but it doesn't work and it creates 3 users with team_id as null for me. (team_id is nullable by default.)

How can I solve this problem using factories?

laravel:10 php:8.1

in User Model:

public function memberOfTeam(): BelongsTo
{
    return $this->belongsTo(
        Team::class ,
        'id' ,
        self::TEAM_ID
    );
}

in Team model:

public function members(): HasMany
{
    return $this->hasMany(User::class, User::TEAM_ID);
}

Each team needs a user_id to be created, which is the manager of that team.

in tests/Feature/Model/UserTest:

    $count = 3;
    $team = Team::factory()
        ->for($this->makeUser(), TeamRelation::MANAGER)
        ->create();
    $user = $this->makeUser()
        ->count($count)
        ->for($team, UserRelation::MEMBER_OF_TEAM)
        ->create();