PDF 2.0 isn’t very relevant currently, because there’s not a lot of software yet that fully supports it. On the other hand, there also hasn’t changed all that much since PDF 1.7. In any case, for generating PDFs it’s best to stick with 1.7 (or earlier) for the time being.
I'm afraid that's the old 2008 spec, which specifies versions up to PDF 1.7.
The current standard is ISO 32000-2, released in 2020, which specifies PDF-2.0. I'd love to get my hands on it, but alas it's paywalled.