Nitpick: Average IQ cannot increase by definition. The median IQ value is defined to be 100 IQ points and one standard deviation in either direction is defined to be 15 IQ points. It's normally distributed so median==average as well. People overall can become more intelligent and the average IQ value will still be 100.

I believe the comment you are replying to is referring to the Flynn effect [1] which shows a ~3 point rise in IQ per decade in absolute terms. That is, someone who is 100 IQ in 1950 would only be 97 IQ measured by 1960 standards.

[1] https://en.wikipedia.org/wiki/Flynn_effect

Yes, the score is always normalized like that, but the Flynn effect shows people getting smarter over time.

So intelligence is increasing while IQ stays the same, to be pedantic.