What is the exact description of the charge?
View your account purchase history here:
View your purchase history for the App Store and other Apple media services - Apple Support
View your subscriptions here:
View or cancel app subscriptions on iPhone - Apple Support
If you do not see the charges on your Apple Account, then it could be that your card has been compromised.
Since you changed debit cards and still see the charges, that would likely mean that it was due to a subscription. It makes no difference if you change cards, because your bank participates in Automatic Billing Updater. If the subscription is not from Apple where you can easily cancel, you can follow up with your bank for removing this charge, where it does not follow you to a different card. For more information on how this works:
https://paymentcloudinc.com/blog/account-updater/