At least two commenters pointed to an article that indicates that the use of genes to predict height has gotten more effective.
Furthermore, the DNA chips used in today’s genome-wide association studies contain a few million variants at most, so these studies cannot even in principle recover the full heritability which is strongly influenced by very rare variants.
This is the answer. Polygenic scores are, for now, based on SNPs. Whole-genome sequencing (WGS) recovers full heritability for height.
As the other commenter put it,
in a short amount of time, we’ve gone from “17%” as “most predictive”, to another study saying 40%, to a new one getting close to the heritability range.