With payments received for tangible goods Paypal would request valid tracking information confirming the item has been delivered to the buyer. As they can validate the tracking information online, once it is delivered they can release the funds. If your friend has received the funds for a gift of money then no tracking number is applicable and Paypal would be unable to release these funds any sooner than the 21 days.
However if they mark the transaction as processed then you may have the option on your account to mark the transaction as delivery/satisfied. If you confirm this by clicking on the "Confirm Receipt" button, the funds may be released to them sooner. This is not always guaranteed. If not then sadly its 21 days.
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