Does anyone know about popular app policies on digital receipts?

I was able to scan a digital receipt from Walmart with my points, giving me enough points to get a $15 Amazon card with the sign up bonus. I did a haggen dasz promo. Sometimes in self checkout I don't have the option to print a receipt.

Fetch Rewards emailed me that they don't accept that.

I also use Shopmium. Ibotta, brandclub, and Merry field has working digital integration with Walmart. Fetch used to too. I wouldn't want to get banned from anything.