Fake merchant

[JAYCOON]

I received and empty envelope and the seller wants it returned before I get my refund. Why do I need to send and empty package?

[kernowlass]

@JAYCOON 

Yep you return what you received, trackable to prove delivery. 

[JAYCOON]

It's going to cost twice as much to return an empty package to china so basically PayPals return policy doesn't help me at all

[kernowlass]

@JAYCOON 

In the event of a dispute you need to bear in mind possible return trackable costs before you buy from that seller / item / country.

Paypal state this >>
PayPal is not obliged to reimburse you for any costs that you incur to comply with any of PayPal’s requests for cooperation for the purpose of resolving the problem (including, without limitation, costs that you incur to return a SNAD item to the Payment Recipient or another party as PayPal requests), although sometimes it may reimburse these costs.

Although they will compensate you for some of the cost if you have activated this at some point before you made that transaction .....
https://www.paypal.com/us/selfhelp/article/what-is-return-shipping-on-us-and-how-do-i-activate-it-fa...

You also have the option to do a chargeback via your card issuer instead of a Paypal dispute if you funded your Paypal payment via a credit card.