What happened
The package passed 513 to 207, comfortably, but only because it was rushed through the old Bundestag rather than the one voters had just elected — a parliament in which the AfD and Die Linke together held more than a third of seats and could have blocked the constitutional change. Merz's team calculated, correctly, that the incoming parliament would not cooperate.
The substantive case for the reform is genuine: European security needs after Russia's invasion of Ukraine, and Germany's underinvested infrastructure, are real problems that the old debt brake arguably made worse. But the sequencing — campaigning against exactly this position days earlier, then using an outgoing parliament to avoid the electorate's actual verdict — fed directly into the AfD's argument that mainstream parties tell voters one thing and do another.