No, they were implementing it at scale for 10+ years. There was an issue with lots of incompatible legacy software so they were still using windows as well but >50% of desks were Linux only.

Then in a very short timespan (1) a new conservative city government came in, (2) Microsoft announced a big local office and (3) the new government killed the open source project without warning and anlunced they'd switch everything to windows 10.

This transition back to windows is now still ongoing and as contracts are signed will not really be feasible to stop. The now new-new Green+social democratic government makes noe a pledge to take open source seriously for all future needs (and I suppose switch back to a Linux asap).