> Forget "white" versus "brown"--Germany is 86% ethnic German.

This number is not entirely correct (it's more like 74% as of 2019, depending on the definition), and it's certainly way more off for larger cities or urban areas in general. You mentioned Frankfurt. Frankfurt am Main e.g. had 54.6% migrants as of 2020.

Some statistics cite Germany as the country with the second most immigrants world-wide, right after the US. (for details, see e.g.: https://en.wikipedia.org/wiki/Immigration_to_Germany https://en.wikipedia.org/wiki/List_of_sovereign_states_and_d...)