I just opened a receipt from Apple for an App Store purchase, and found that GMail is adding a "receipt summary" (for lack of a better term) to the message view, above the sender/time received header:
I don't think this was present a week or two ago when I last received one of these receipts, and I just checked an older receipt and it is now present; I'm assuming this is a new Gmail "feature". I looked through Settings but didn't find anything that looked likely to control this. How can I disable?