Is the exponent bias $2^{n-1}-1$ or $2^{n-1}$ I'm a bit confused with the exponent bias. The sources I found online claim that it is either $2^{n-1}-1$ or $2^{n-1}$, $n$ is the number of bits used for the exponent. In my book when given examples on the bias of a 32bit system the bias is said to be $2^7$ which means the bias is $2^{n-1}$ while in an example on the bias of 64bit the bias is said to be $2^{11}-1$ which is $2^{n-1}-1$

So which one is it?
Both encodings for the exponent are possible, and they are called Excess-$2^{n-1}$ and Excess-$2^{n-1}-1$ - in particular, you might meet such number encodings as Excess-127, Excess-128, Excess-1023 and so on.

The IEEE-754 standard happened to choose the Excess-127 and the Excess-1023 encodings for exponents, so these encodings became more customary. Your book is not mistaken about the exponent bias, it just follows a way, different from this standard.

You can find additional information and nice graphs here.