Reports about the city of Munich authorities that are considering the replacement of Linux with Microsoft products mostly comes from one man, the Deputy Mayor of Munich, who is also a long-term self-declared Windows fan.
Munich is the poster child for the adoption of a Linux distribution and the replacement of the old Windows OS. It provided a powerful incentive for other cities to do the same, and it's been a thorn in Microsoft's side for a very long time.
The adoption of open source software in Munich started back in 2004 and it took the local authorities over 10 years to finish the process. It's a big infrastructure, but in the end they managed to do it. As you can imagine, Microsoft was not happy about it. Even the CEO of Microsoft, Steve Ballmer, tried to stop the switch to Linux, but he was too late to the party.