That's an utterly nonsense claim. The time sensitivity of data is highly context dependent and even if it's true that the real estate trends of 2019 won't help

That's an utterly nonsense claim. The time sensitivity of data is highly context dependent and even if it's true that the real estate trends of 2019 won't help you predict 2022, it's crazy to assume that "overfitting" to 2021 will do better. I mean even this exact example. You think the patterns of 2021 peak covid real estate are a good example to learn from for 2022? No, absolutely not.