DuckDuckGo staff here. As mentioned in the linked page, the purpose of the request is to retrieve a website's favicon so that it can be displayed in certain places within the app or on the results page. We use an internal favicon service because it can be complicated to locate a favicon for a website. They can be stored in a variety of locations and in a variety of formats. The service understands these edge cases an…
This doesn’t make sense for a browser: just embed the service’s logic in the browser, the browser has all the same information the service could get.
The service is private as we do not collect any personal information (e.g. IP addresses) on any requests for this or any service and the requests are all end-to-end encrypted.