Even though this is from 2018, it was and still is completely applicable to every other investment bank out there.

Investment banking organizational structures are set up such that bureaucracy encourages 'silos' where teams can deliver quicker if they don't depend on other teams, and performance related pay dominates the managers (managing directors) thinking.

Having worked at Megabank, it ran at least one system on SunOS (not Solaris), well into the late 2010s. It had Windows XP, long after end-of-life.

Nothing about that story is peculiar to DB.