Every time you visit a website on the Android version of the browser, instead of requesting the favicon from https://example.com/favicon.ico, the app is calling out to https://icons.duckduckgo.com/ip3/example.com/favicon.ico.

Since DDG owns the icons.duckduckgo.com service and the domain you were interested in is in the request to icons.duckduckgo.com, you've sent the domain to DDG's servers.