My ViewController WITH Large Navigation Bar Scrollers up automatically After loading WKWebView

In my app, I am loading about the page in a view controller with a WebKit WebView, and Viewcontroller has a Large Navigation Controller. At time of view DidLoad Large navigation bar is shown fine.

At this point when I start loading my WebView with a local HTML file. After loading this WebView, without any user interaction, ViewController automatically scrolls up such that navigation bar shrink to actual small-sized form.

from My ViewController WITH Large Navigation Bar Scrollers up automatically After loading WKWebView