Death to NATO

What they all have in common is that they're incumbents. The article this appears to be from is paywalled, so we don't know what all the data points are. There could be some countries in there that don't support Ukraine, or that support it so little it wouldn't be a real factor in their elections.

I'm very skeptical of Ukraine (and Palestine) having major direct impacts on the U.S. election because of how little most voters care about any foreign policy issue, sometimes even when it's U.S. troops directly fighting.

This seems like a worthwhile observation from the comments, though:

Anything that happens in the world gets blamed on the incumbent and than amplified by politically adjacent media sources

No such thing as an “incumbent advantage” anymore given how effective constant negative coverage from oppositional media is