I've read different things, about the cut content, but how do we know what was really cut and what was never ingame? Are these just things like a subway or car customization, or is there really an evidenz that they cut some things of the main story? Perhaps some of these things are always planned for the DLC's
I suppose it depends on when you define content as planned or actually cut. DEUS EX: MANKIND DIVIDED wanted to have a DLC at the start of the game so they literally extricated a vital plot mission from the story (the game is about investigating a terrorist attack, they removed the mission about you finding out who carried it out) then presented it as free DLC. That's certainly cut content as it was in the game and removed.
However, obviously you can plan any number of things that might be unfeasible or things you just decided not to include.