React Native IAP Auto Renewal Subscription check Expiration

I am trying to restore and detect the end of auto renewal subscriptions on iOS using https://www.npmjs.com/package/react-native-iap/v/4.0.8 By calling getAvailablePurchases() I get a different number of purchases everytime I invoke this function (e.g 7, next time 23, then 4..). This makes no sense to me. I know the subscription renews any 5 minutes for monthly subscription. My idea is to get the latest purchase and just check the expired dates in the receipt from this one. (at the moment I am parsing over all of them, this cannot be best practice). Another thing is that I detect several active purchases with different transactionReceipts eventhough there is just one active.

RNIap.getAvailablePurchases().then((purchases) => {
            if(purchases != undefined && purchases.length > 0){
                alert(purchases.length + ' purchases');
                purchases.forEach((purchase) => {
                    const receiptBody = {
                        'receipt-data': purchase.transactionReceipt,
                        'password': appSubscriptionId
                    };
                    RNIap.validateReceiptIos(receiptBody, true).then((result) => { // false for production
                        let from, to, lastRenewal = '';
                        if(result.status == 0){ // 0 means receipt is correct..
                            result.latest_receipt_info.forEach((info) => { 
                                if(this.dateIsInFuture(info.expires_date)){
                                    to = moment.utc(info.expires_date, "YYYY-MM-DD HH:mm:ss").toString();
                                    from = moment.utc(info.original_purchase_date, "YYYY-MM-DD HH:mm:ss").toString();
                                    lastRenewal = moment.utc(info.purchase_date, "YYYY-MM-DD HH:mm:ss").toString();
                                    this.setState({ premium: true, from: from, to: to, lastRenewal: lastRenewal});
                                }else{
                                    alert('nicht aktiv');
                                }
                            });
                        }
                    }); 
                }); 
            }else{
                alert('No purchases found');
            }
        });