Early Medieval 'Slavic Period' (~600-900 AD) samples from southern Poland and northern Ukraine had variable levels of Germanic, Balkan, and Greco-Roman ancestry, as per the recent study on Slavic migrations (Gretzinger 2025). I think these early Slavs also had Scythian and minor Uralic ancestry.

It's currently unknown whether or not these samples represent the Proto-Slavic population, but I suspect that they don't.

They were found in close geographic proximity to the theorized Proto-Slavic homeland, but the Czechia_EarlySlav sample (also from the early Slavic Period) has significantly less Balkan, Germanic, and Scythian ancestry. I suspect that the Proto-Slavs were more similar to this sample — i.e. more Baltic-like — than those from Grodek and NW Ukraine.