This seems… reasonable…? They’re not telling you not to do this. It’s a safety measure in case 1. You either fat finger the tip screen and don’t realize it or 2. You write a $5 tip on your receipt and the waiter rings it up for $50. It probably triggers after 25 or 30% on a tip. Who cares?
I don’t really get a lot of people on this website. This is just a good faith, consumer friendly security check email and people will still read it and find a way to feel morally superior about it