r/MachineLearning - [D] What Machine Learning concepts would you like visually explained?

Although the existing guide is very good, it lacks a good explanation of the Decoder side. It simply says that it is very similar to the Encoder without really provide much detail. In my eyes, the whole "magic" of the transformer is the ability to have different input and output lengths! That part is poorly explained, simply saying that the Decoder is using the Key and Value of the Encoder is not enough because it doesn't explain how the different dimensions are mitigated.