Construct switched to WKWebView years ago. We already set Cordova builds to use WKWebView only as well, to make sure Cordova removes all references to UIWebView.
There may still be certain addons that reference UIWebView. (They don't even need to actually use it, the message appears to be shown for anything that merely contains references to UIWebView.) It's difficult to help further without knowing which addons these are though.