It's probably more than one thing. I agree with with the points on supply, plus the fact that cities can only grow so much before transportation becomes impossible, and then there is a huge premium to be near the center (watch the traffic in the streets in old movies or documentary from the 1970s compared to now in cities like Paris or London).

But I think another big factor is that we are measuring inflation wrong. I think the various QE had the same effect than any other money printing in history, to drive prices up. But I think the way it was introduced (directly in the financial system, rather than paying people with it), meant that the inflation was localised into financial assets, and to the cost of anyone benefiting from higher financial assets (VC, asset and hedge fund managers, etc). So stock prices skyrocketed, as prime real estate prices, college tuitions, expensive restaurants, etc. But that's not captured by the various CPI indices.

Then came covid, with its new, massive rounds of QE. But this time the money printing was distributed to ordinary citizens through various furlough schemes, financed by deficits, pretty much directly financed by the central bank. And oh surprise, about a year later we see inflation jumping up massively.

So it may be that these inflation adjusted real estate prices charts aren't adjusted as they should.