Open external links in browser app - domain url

[JonnyTech]

In global web app settings, I enable open external links in browser app.

Then I add a web app link to start.duckduckgo.com (the clean homepage).

This should give me search results in native alpha and links to open externally.

Unfortunately, search results open externally, even though the results page is the duckduckgo.com domain.

Is the app not capable of detecting that the domains match or am I doing something wrong?