The far-right Alternative for Germany and the left-wing populist Sahra Wagenknecht Alliance both won substantial gains in Sunday's state elections. Both parties have close ties with Russia and oppose support for Ukraine.
What is particularly interesting about this is the fact that the AFD is extremely right-wing and has blatant fascist tendencies, while the BSW emerged from the left-wing camp, from a wing that has more communist ideals. Ideologically, these parties could hardly be more different.
They have quite a few commonalities: both oppose minorities, both are nationalist, both have autocratic tendencies, both are Putin-friendly. The only major difference is that BSW does include top-to-bottom redistribution in its platform while Afd is a staunch supporter of bottom-to-top redistribution.
I wouldn’t consider BSW as a classical left-wing party, though (also rejected by BSW, but I think smaller/new parties usually try to avoid classifying themselves in the left-right-spectrum). Sociopolitically, their positions appear (not much substance so far) to be more closely align with the conservative-/right-wing-end of the political spectrum.
The comment you replied to doesn't actually say BSW is left, just that they emerged from the left, specifically the part of the left that is mentally stuck in the GDR.