So…. You didn’t read the article, and it shows. Maybe it is on to something.

For reference:

Gen Z is the first group to score lower than the generation before them. Their attention span, memory, reading and math skills, problem-solving abilities, and overall IQ are lower than those of millennials.

All of these things are quantifiable.

No that doesn’t make IQ a good measurement of intelligence. Volumes have been written on this and how it is more a measurement of one’s heritable environment. Source: I am a millennial with an above average IQ.

And again…. They tested for more than just IQ. Read the article. Try and understand it.

Both things can be true: that IQ is not a good index to use in this context and that other measurements have shown cognitive decline.