Select field : problem with getOptionLabelFromRecordUsing()

// UsersResource.php (Filament Ressource)
Forms\Components\Select::make('interview_by')
  ->relationship('interviewBy', 'firstname')
  ->getOptionLabelFromRecordUsing(fn (User $user) => $user->getNickename())

// User.php (Model)
public function getNickename(): string
{
  return "{$this->firstname} {$this->lastname}";
}