Lumen save() is not working after an other save()

I have these two Models :

Club.php

class Club extends Model implements AuthenticatableContract, AuthorizableContract, JWTSubject
{
    use Authenticatable, Authorizable;

    // because name of the class != table name
    protected $table = 'sf_club';

    /**
     * The attributes that are mass assignable.
     *
     * @var array
     */
    protected $fillable = [
        'login', 'email', 'nom_equipe', 'avatar', 'nation_id', 'argent',
    ];

    /**
     * The attributes excluded from the model's JSON form.
     *
     * @var array
     */
    protected $hidden = [
        'password',
    ];
}

Stade.php

<?php

namespace App\Models;

use Illuminate\Database\Eloquent\Model;

class Stade extends Model
{

    // because name of the class != table name
    protected $table = 'sf_stade';

    /**
     * The attributes that are mass assignable.
     *
     * @var array
     */
    protected $fillable = [
        'club_id', 'prix_place', 'capacite', 'entretien',
    ];

    /**
     * The attributes excluded from the model's JSON form.
     *
     * @var array
     */
    protected $hidden = [
        
    ];
}

In my database the field club_id from Stade table is a foreign key linked to table Club column id.

I have a method in my controller called Register, this is the method :

public function register(Request $request)
    {
        //validate incoming request 
        $this->validate($request, [
            'login' => 'required|string|unique:sf_club',
            'email' => 'required|email|unique:sf_club',
            'password' => 'required|confirmed',
            'nom_club' => 'required|string|unique:sf_club,nom_equipe',
            'nation_id' => 'required|exists:sf_nation,id'
        ]);

        try {

            $club = new Club();
            $club->login = $request->input('login');
            $club->email = $request->input('email');
            $plainPassword = $request->input('password');
            $club->password = app('hash')->make($plainPassword);
            $club->nom_equipe = $request->input('nom_club');
            $club->nation_id = $request->input('nation_id');
            $club->argent = $this->argentDepart;
            $club->save();

            $stade = new Stade();
            $stade->club_id = $club->id;
            $stade->save();

            //return successful response
            return response()->json(['user' => $club->nom_equipe, 'message' => 'CREATED'], 201);
        } catch (\Exception $e) {
            //return error message
            return response()->json(['message' => 'User Registration Failed!'], 409);
        }
    }

The problem that I have is that the Club model is saved correctly after the $club-save() but the function return a 409 error and the stade is never saved. My question is : why the Stade is not saved after $stade->save() ?

Thanks in advance

source https://stackoverflow.com/questions/70414121/lumen-save-is-not-working-after-an-other-save