Press the key to the left of 1 (not the numpad) or the right of the Eszett (sharp S) on the German QWERTZ keyboard and you probably hit a dead key. There are dedicated keys for the German umlauts and Eszett but these are for French accents in loan words: â, á and à, e.g. as in Café.
It's worth mentioning of course that there are no-dead-keys variants of the keyboard layout but this has been pretty much the norm on Windows since the 1990s I think.
It's worth mentioning of course that there are no-dead-keys variants of the keyboard layout but this has been pretty much the norm on Windows since the 1990s I think.