Google is tracking everything you ever bought via email receipts. Marcus has demonstrated this on Mastodon with screenshots from his account's takeout.
You can check what Google has stored in your purchasing history under Purchases when logged in to your Google account.
However, if you want to delete your purchasing history, you also need to delete the emails (receipts), from which Google is scraping the information from. Thus, it becomes impossible to store your email receipts without also enabling Google to scrape this information.
This form of tracking and profiling is possible because Gmail does not encrypt your data. The company can see, filter and use all the information you store in your Gmail account.
Google scrapes your purchasing email receipts for valuable information to create a purchasing history linked to your account. The data is classified as price, currency, delivery address, description, vendor, and more. This purchasing list contains a lot of sensitive information, and it is possible that Google uses this data to create a profile about you and your purchasing habits.
While Google says that they don't use any information from Gmail messages to serve ads, including the email receipts and confirmations shown on the Purchase page, there is no guarantee that this data is not being used for optimizing advertisements.
After all, it is Google's business model to know everything about you so that they can display targeted ads when you are surfing the web. While Google is trying to meet rising privacy concerns, this business model has remained unchanged and contradicts a truly privacy-friendly approach.
This purchasing history is yet another 'feature' by Google that seems not be made for the users - no one really knows that such a purchasing history even exists in their accounts - but for someone else.
What is worse: If you want to delete your purchasing history, it becomes a very tedious task. Here is a step-by-step guide on how you can delete your purchasing history in Gmail:
From the Google Purchases page, select a purchase you want to delete.
At the bottom of the payment detail page, select Remove Purchase.
To remove the purchase in the history, you need to delete the email receipt. Select View Email to open the matching email for this purchasing item.
The email opens in your Gmail account. Select the trash icon to delete it.
Repeat step 1 to 4 for each purchasing item in your history.
The next time Google performs a scan of your inbox for purchases, every deleted purchase will be removed from your purchases history.
While there are guides that explain how you can stop Google from scanning your receipt emails to create a purchasing history, this settings configuration is pointless. After all, Google will still have all your receipt emails easily accessible and can still scan them to create a purchasing history - whether you would like this list displayed in your account or not.
The only way to truly stop Google from creating a purchasing list based on your receipt emails is to stop using Gmail.
Feel free to try Tutanota, the privacy-friendly alternative to Gmail. 😀