As far as I can tell parcelsapp is just a universal tracking site like many others. I have used to to track packages when I was not sure which service was being used.
Not all shipments receive timely acceptance scans. If your package is coming from outside the US, it is not uncommon for a USPS tracking number to show no data until the package reaches the US and is scanned by USPS.
A false tracking number is only useful to a scammer if it shows delivery near you -- in other words, it has to be a real tracking number, just not for a shipment to your exact address.
If nothing arrives by the last estimated delivery date and tracking does not show delivery, you can file an "item not received" claim with eBay. After three business days you can ask eBay to step in and force a refund for up to twenty-one business days from starting your claim.
If tracking shows delivery but nothing arrives, contact the shipping service used and see if the tracking corresponds to a delivery to your address. If not, and if you can get some documentation of that, contact eBay via social media and mention that you have a case of "false tracking" and you should have the opportunity to share your documentation.
