It isn't. TPM 2.0 was standardized in 2015; the most recent update to the standard was published in 2019.

I stand corrected. Still, 2015 isn't that long ago, and new systems of the time couldn't adopt it immediately.

Would be odd for MS to do so - according to other news, W11 could run with TPM 1.2, so apparently they didn't increase their requirements that much. Even that would leave quite a few systems out...