Soros being a left-wing financier is a necessary but not sufficient condition for this not to be antisemitic.

The other question I'd have asked is whether this is actually funded by Soros or not? If Soros is behind this then he seems fair game to be criticised as an individual and not a race.

If on the other hand he's not actually behind this and people are just pinning this on a Jewish bogey figure then yes that does have the whiff of antisemitism still.