I have spoken privately with @Adam2 who has given his consent for me to publish the result of my investigation here so that we don’t leave the rest of you in suspense
It seems that in this instance, the merging of the prepaid account with the new current account has included the amount of money which was migrated from one account to another as being “Spent”, despite the feed item being suppressed.
We have had a few reports of this, but not a considerable amount. If anyone else has a report of this potentially being the case for them, let me know. It’s not a huge issue since it would only be present on the first day of upgrading, but I will give the product team a heads up that we’ve had another instance of it