I was looking for the same answer. I just watched this video: https://developer.apple.com/videos/play/wwdc2022/10041/ Around 26:50 it's about the identity Apple Wallet buttons and I tried it out for the PKAddPassButton, it's the same principle (checked in iOS 15.5): The button itself decides, if the title label has one or two lines, depending on the space it has.

Seems like a Bug in WebKit for me. I don't use admob and WKWebview ist not on the first ViewController. The App can be used without the warning until a WKWebView is called for the first time. Then the warning appears. So these lines of the thread seems the important one: