Picture metadata
Why does this picture my wife received from me say “saved from quick look” if I didn’t use the app or ever download it? I took it with my iPhone 7 and this is what she sees on her phone.
iPhone 7 Plus, iOS 15
QuickLook isn't exactly an app-- it's what happens when you take a quick look at a file. In Finder, when you select a picture file and push the spacebar, you can get a quick look at the picture without having to open it in Photos or Preview or another viewer. In the upper right of the image below, you can see icons that let you mark up the picture, rotate it, open in your favorite editor, or share the picture. I've opened the share menu, here, where you can mail, message, airdrop, etc. the picture to a friend.
I'm guessing your wife used got the picture to you though some process that incorporated the quick look routine.