About the normalization in the "TimeSeriesDataGenerator" class

[beijiguang94]

In the "_preprocess" function of the "TimeSeriesDataGenerator" class, why are there two types of normalization methods (specifically, the minmax normalization method for the "electricity" dataset; the other normalization method for the other time series datasets)?
Is the second normalization method reasonable? Because it involves the other variables' information when scaling a single variable.