Per your first link, the US is below the OECD average with a -13 delta from 2018
I'm not saying that's a good thing. We're a very rich country and we should do better.
But the US also has a lot of systematic problems that peer countries don't, like child poverty, that are likely a bigger cause of subpar test scores than bad schools.
Merely focusing on "below average" without acknowledging the trend -- declining -- seems to be disingenuous.
There's also the matter of picking a definition for third world.