I work in "online payments for guns" and it's amazing how many innocent people get banned by PayPal over guns. I talk to at least one per week. In almost every case, these people simply weren't aware that PayPal prohibits firearm transactions. Although PayPal doesn't provide much warning, it is actually following an industry-wide practice. All the payment platforms prohibit guns [1].

[1] https://www.guntab.com/payment-platform-firearm-policies