My question is not if the funds go somewhere else.
My question is, the mere fact that it's not you giving directly. You're giving to the PayPal giving fund, and they in turn are granting your request to give those funds from their giving fund to the non profit designated, does that result in a halachic change, regarding you fulfilling your Maaser or tzedaka requirements, cause you're not giving your money directly to a moisad, rather to non Jewish recipient, who in turn (with that toivas hano'oh?) will pass it on to a Jewish moisad.
If they were guaranteeing to pass it on, they are just a shliach, like the mailman who delivers the check.
But since it's not guaranteed, perhaps the status changes.