[1]: https://journals.sagepub.com/doi/full/10.1177/17456916156099...
[2]: https://osf.io/ezcuj/wiki/home/
[3]: https://science.sciencemag.org/content/349/6251/aac4716.full...
You should have very little confidence in the predictive power of most psychology findings since the founding of the field.
If someone says that IQ is unreliable, they're likely right just given the track record of that field.