⭐ Merited by suchmoon (4)
I was complete noob too when i found out that Bitpay uses security protocol(its used to prevent phishing or typing incorrect btc address ). In order to pay an invoice you need to scan the QR code. If i knew whats the merchant btc address i would've sent the money directly from my desktop wallet with high fee,but they force you to use their wallet and receiver's btc address is always a link,not an actual btc address,thats the difference . 
There are a few tools available on the internet which decode the sheme to a standard bitcoin address.
One of these tools can be found here: https://alexk111.github.io/DeBitpay/ (Source code: https://github.com/alexk111/DeBitpay).
You will be able to derive the address the funds need to be sent to with this tool.
Then you can skip the process of sending your funds from your desktop wallet to your bitpay mobile wallet, and send it directly from your desktop wallet instead.
Note that i haven't tried this tool out and can't guarantee that it is 100% working. However, it seems to have quite good reputation and is mentioned quite frequently.