Slack occasionally (2-3 times per day) sends notifications about purchases that happened before RC integration (a few years ago purchases).
I have an Android app and started using RC a few months ago.
Slack sends me notifications about purchases which are just purchased, but also for purchases from a few years ago.
I don't see any pattern, but the attached screenshot was captured at 6am on June 10th, 2024. You can see slack sent a purchase that happened in 2022.