In the chapter about the Grover algorithm, it is suggested that the gate which executes the phase shift is given in the following form:
Now I have looked at this gate in detail and come to the conclusion that this "only" negates the state $|00\rangle$, but not all others, this can be shown for different inputs $|00\rangle$, $|01\rangle$, $|10\rangle$, $|11\rangle$ (the gate changes only $|00\rangle$ to -$|00\rangle$) or see here. I'm sorry, because in the chapter it says a few pages earlier: $|x\rangle$ becomes $-|x\rangle$ and $|0\rangle$ remains to $|0\rangle$ (picture left section). But that does not correspond to the circuit (picture right section). That's why I ask myself, what is right now? I want to do this a bit further, we say the Grover operator is:
$$H^{\otimes n}(2|0\rangle\langle 0|-I)H^{\otimes n}$$
That means I have several Hadamard transformations before and then do the phase shift, followed by Hadamard transformations. I think that you can see this in $(2|0\rangle\langle 0|-I)$ (matrix with 1 in the first row, all other rows -1), that $|x\rangle$ becomes $-|x\rangle$ and $|0\rangle$ stays $|0\rangle$. But that does not correspond to the circuit (picture right).