> It will get a software update and will charge faster in no time.

This is certainly possible, especially if the reason for the slow charge is that the cells were rushed into production so fast that Tesla didn't have time to characterize them, and don't know what charge conditions will damage them. On the other hand, the 4680s have been in production, in one form or another, for quite a while now, including in Model Ys which show the same slow charge performance, so it's also certainly possible that the cell quality is such that they can't be fast charged without damaging them, regardless of software tweaks.