The fact is that the Indo-Europeans initially had a Siberian component through their ancestors - eastern hunter-gatherers. Pay attention to the graph, EHG carries a rather large Siberian component - at least 5-10% by eye. In calculators, it is hidden, only an additional late admixture appears. SSA, unfortunately, is absent from the Indo-Europeans initially.
https://i.ibb.co/WDFRH0Q/EHG.jpg

