Maps and Photos let you enter your credit card info to buy stuff in the app (you can order food in Maps and prints in Photos).
This is not unusual. Every app that offers food delivery or prints lists "financial info" on their App Store privacy label. And if you drill down into the details, it's specifically payment information.
As far as I can tell, the Gmail app does not collect financial info (it's not in the App Store privacy label).
I believe this is why Amazon no longer includes what you bought in their order status (confirmation, shipped, delivered) emails (an annoying change, imo)
They also wanted to eliminate the receipt brokering businesses. A couple of companies were tracking purchases and allowing users to call for refunds when prices suddenly dropped after purchase.
This is not unusual. Every app that offers food delivery or prints lists "financial info" on their App Store privacy label. And if you drill down into the details, it's specifically payment information.
As far as I can tell, the Gmail app does not collect financial info (it's not in the App Store privacy label).