why does apple keep charging me??

please don’t tell me it’s unknown subscriptions i have checked multiple times and i have no subscriptions. every time i go to download an app it asks me to sign in and then acts like it’s going to let me install it then asks for me to verify by adding a payment method. i add my card and as soon as i add it apple tries taking $16.17 from me. it has never asked me to verify with a payment method before but whatever. every time it tries charging me it fails my card so i have to re type my cvv in to download the app and here it goes trying to charge me again failing my card once more. it has charged me 30 different times. i literally had to block apple on cashapp so it would stop but it still tries taking money from me.