I only have two mojave’s and this is only their 2nd winter but mine have faded quite a bit, especially in the winter it seems.
Sorry I don't have more experience to answer your question and to complicate things one of mine is a combo and it's possible the other is too.
Here is the one that I think is just mojave from last summer, already a lot of fading:
If I can find all my batteries and have time I'll get a picture today as much more faded for some reason. He is a breeding male now so maybe that has something to do with it.