There are also bottleneck in European IE populations. For example, both Poles and Lithuanians are Balto-Slavs, but Lithuanians have obtained far more non-IE-hg (N) than Poles. However, there are not much Uralic substratum in Lithuanian language. In the case of Anatolian, it has lost subjunctive and optative, probably due to substratum, which is more "probably" than Lithuanian linguistically.
Regarding the PU genome, this blog gives a detailed answer.
https://eurogenes.blogspot.com/2021/...kra001-no.html