PayPal won't process any payments for ammo or firearms. They've got those merchant codes blocked. You can use it on Bass Pro (I think) for everything but ammo and firearms.
Hopefully it was just a glitch with them and USAA. We use USAA as a funding source on our PayPal account and haven't had any issues. Only issue I've seen with CashApp is if you use their card it will sometimes be seen as a foreign issued card and be declined by some processors.
Good info. As for a CashApp card, I don't think she has one of those. I'm not sure, but the wife might have had her PayPal app for paying our lot rent linked to our checking accounts instead of the credit card. But, after the denial on the ammo, she decided that we didn't need their card, but instead, she got a CC from USAA.