Thanks for your reply.

I asked a friend of mine for the same question, then he showed me his paypal account.

On the 30th of Nov, he withdrew nearly all the balance to bank account, only about 50 cents was left in Paypal.

On the 1st of Dec, there was a return request opened for $24.87

On the 3rd of Dec, he sold another item and received $29.45 (after paypal fee)

But now, there is only $5.01 left, shown as "Total".

So from the looks of it, the $24.87 was still deducted?