Ah, okay, makes sense (in an evil way).
It just sounded like it was a sudden wave after the site had become more popular, but it maybe just appeared on the radar of scammers as well as the competition.
I have long stopped telling people whether their charge worked if an order looks suspicious, to prevent them from getting this information. So that wouldn't work now.
I am not sure I follow, could you clarify? You do send a confirmation after sign up I presume?
Well I can't say "your payment was processed successfully", because that would give information to people who want to test cards. Rather I manually read through the orders, and only contact people if something went wrong with their payment AND the order doesn't look suspicious.
Are you on Stripe?
Can't find it but he had a whole blog post about it
Hence charities are popular to test on too.