I am not sure, but think it is a code number, not a QR code. Read what ebay say, below. Ebay app. has to be used to get QR code.
For proof of collection you can choose one of these options:
- On desktop, manually enter the buyer's 6 digit code in View order details
- Use the eBay app to scan the QR code the buyer received through email
- Use the eBay app to manually enter the 6-digit code the buyer received through email
- Ask the buyer to confirm they’ve collected in person through the item’s order details