You will have to call customer services on 202 to check that out but I noticed a similar issue on my account as I had fingerprint authorisation turned on for iTunes purchases
What was happening was that I pressed the home button to exit but because of fingerprint being on I was authorising purchases!
I have no affiliation whatsoever with O2 or any subsidiary companies. Comments posted are entirely of my own opinion.
This is not Customer Service so we are unable to help with account specific issues.Currently using:
Pixel 7a (O2 & Lyca), One Plus 6 (Sfr), iPhone 12 Pro Max (Vodafone)