Personal understanding, in TensorFlow domain, logits are the values to be used as input to softmax. I came to this understanding based on this tensorflow tutorial.
https://www.tensorflow.org/tutorials/layers
Although it is true that logit is a function in maths(especially in statistics), I don't think that's the same 'logit' you are looking at. In the book Deep Learning by Ian Goodfellow, he mentioned,
The function σ−1(x) is called the logit in statistics, but this term
is more rarely used in machine learning. σ−1(x) stands for the
inverse function of logistic sigmoid function.
In TensorFlow, it is frequently seen as the name of last layer. In Chapter 10 of the book Hands-on Machine Learning with Scikit-learn and TensorFLow by Aurélien Géron, I came across this paragraph, which stated logits layer clearly.
note that logits is the output of the neural network before going
through the softmax activation function: for optimization reasons, we
will handle the softmax computation later.
That is to say, although we use softmax as the activation function in the last layer in our design, for ease of computation, we take out logits separately. This is because it is more efficient to calculate softmax and cross-entropy loss together. Remember that cross-entropy is a cost function, not used in forward propagation.