which seems relevant to your question. There are others, for example…
Hope it helps
EDIT: after reviewing the updated exercise notebook on github I see that the narrative markup is much more explicit than it used to be about the units for housing price (hundreds of thousands) than it once was. In the old days, the problem was almost always that models were predicting near 400 instead of near 4. That is what the threads I linked above discuss. My understanding now is that is not the issue raised by the OP in this thread. Rather, it seems to be an implicit requirement that the number of rooms training data vector is ordered and starts with 1.