berlin is the most populous city in germany no…

berlin is the most populous city in germany not second

Who said it was second?

Berlin with a population of 3,748,148 in 2018 was the largest city in Germany and the 2nd-largest in the European Union after London/UK, which technically is out now.

More EU cities: https://en.wikipedia.org/wiki/List_of_cities_in_the_European_Union_by_population_within_city_limits

More German cities: https://en.wikipedia.org/wiki/List_of_cities_in_Germany_by_population