According to the data, the film was first released in West Germany in 1972 by Centfox. I found some German material with different titles. Which ones actually belongs to this first release?

https://i.ebayimg.com/images/g/N6UAAOSwNWxe4laM/s-l1000.png
https://www.vintagemovieposters.de/bilder/2013032719271967893_supersize.jpg
https://cdn.premiumkino.de/movie/3819/92b41a65b7ca15e1a8aee8307d59d884_w1200.jpg
https://www.vintagemovieposters.de/bilder/2013032719251850865_supersize.jpg
https://images.booklooker.de/x/00At5t/Brennpunkt-Brooklyn-Film-f%C3%BCr-Sie-Nr-35-74.jpg

According to this poster database, these two posters represent the first German thetrical release ('Brennpunkt Brooklyn' + THE French Connection [OT]):

https://www.filmposter-archiv.de/filmplakat.php?id=3570 https://www.filmposter-archiv.de/filmplakat.php?id=18370

This poster is listed as a re-release poster (apparently after the Academy awards). This poster has 'French Connection [missing the 'The' from the OT] - Brennpunkt Brooklyn' for the title.

https://www.filmposter-archiv.de/filmplakat.php?id=24437

Okay, thank you. Why do you believe should be "Brennpunkt Brooklyn" rather than "'Brennpunkt Brooklyn - The French Connection"?

For my understanding, 'The French Connection' is just the original title and therefore not part of the German title. Maybe 'Brennpunkt Brooklyn - The French Connection' could be another AT (poster title). Besides that, three of the promo material images you have linked also use 'Brennpunkt Brooklyn' only.

German wiki article: https://de.wikipedia.org/wiki/Brennpunkt_Brooklyn German film database: https://www.ofdb.de/film/2993,Brennpunkt-Brooklyn

It looks like the German AT 'French Connection - Brennpunkt Brooklyn' came up after the movie was having success and was re-released.