First of all, this problem occurs with apps that use the admob library.
Among the apps I sell, there is a paid app with a different target (same code) in the same project.
When I build this paid app in my project, I don't see this warning.
My paid app uses "Other Swifts Flag" to not include the admob library in the code from the build generation, and the admob library is not included in the app.
I contacted Admob and got a reply.
Admob is also aware of this issue.
Admob believes it's a bug by Apple, and Apple is also aware of this bug.
Maybe it will be improved in the next Xcode or iOS update.
My guess is that when using WKWebView in Admob, you get such a warning message.