Some virus scanners have gone full retard and flag all executables they haven't seen before.

Hurm -- I just had Avira and Windows Defender flag it as unsafe. They both said they detected Adware/Filefinder.IL

Is that a common missed signature? Does it have a common pattern?

No idea, to be honest. I'm not really using Windows actively any more, but complaints about heuristics detections crop up all the time.

EDIT: I've just uploaded a test electron binary I made myself to see whether it triggers on all of them. 0 detections for mine, but mine are always digitally signed. I'm not sure whether and how that affects heuristics, but theoretically it should.