That’s very interesting. It shows that the DuckDuckGo “Browser” is just using the OS provided webview renderer 
A quick Google search tells me:
The DuckDuckGo browser uses WebView, the OS-provided rendering engine.
In its essence, it’s just a UI slapped on to WebView, which is why it’s so small. At the moment, the only WebView options are Chrome and Chromium, so basically, DDG uses Chrome/Chromium. AOSP has Chromium, but I’d imagine most phones would ship with the Chrome WebView.
So the problem is that your OS webview is not up to date. I think the app you need to update is