Obviously scientists have thought about that and therefore administer age-adjusted IQ tests for different cohorts, precisely with the aim of IQ staying constant during aging of an individual. And yet here we are.

You really don't need a censorship conspiracy to explain these things. I'd recommend you try to challenge your assumptions about IQ and heritability by downloading a few textbooks about the topics. Many many papers are freely available, and the textbooks are let's say easy to find. You could try textbooks about a more accessible area like developmental psychology as it is more easily accessible and still covers these topics quite well.

The problem with the "I'm right, you are wrong, educate yourself" reply is that, because of the taboo, different books will say vastly different things about this topic. So you have to decide which books are the "good" ones and which are the "bad" ones.