osb/app/Traits/ProviderRef.php

<?php

/**
 * Get a provider reference ID
 */
namespace App\Traits;

use App\Models\ProviderOauth;

trait ProviderRef
{
	public function provider_ref(ProviderOauth $poo): ?string
	{
		return (($x=$this->providers->where('pivot.provider_oauth_id',$poo->id))->count() === 1)
			? $x->pop()->pivot->ref
			: NULL;
	}
}