IQ has plateaued or gone down for some western countries while continuing to rise elsewhere
You’re describing the “Reverse Flynn Effect”, which is still hotly debated as happening at all much less happening to this day. And it’s got nothing to do with modern-day school performance listed in OP’s image. The Flynn Effect is more neatly tied to the Lead-Crime Hypothesis, having emerged in the 1990s and largely restricted itself to post-industrial nation states.
You’re describing the “Reverse Flynn Effect”, which is still hotly debated as happening at all much less happening to this day. And it’s got nothing to do with modern-day school performance listed in OP’s image. The Flynn Effect is more neatly tied to the Lead-Crime Hypothesis, having emerged in the 1990s and largely restricted itself to post-industrial nation states.
I was replying to you, and you were discussing IQ.
Also, not hotly debated, but more complicated: https://personality-project.org/revelle/publications/dworak.23.pdf