Lots of doubt in the discussion here. I found this, and it’s not quite as elegant an explanation, but it seems to agree that it is due to chromatic aberration a

Lots of doubt in the discussion here. I found this, and it’s not quite as elegant an explanation, but it seems to agree that it is due to chromatic aberration and the eye being tuned to focus on red and green light. https://www.thenakedscientists.com/articles/questions/why-are-blue-lights-harder-see https://www.thenakedscientists.com/articles/questions/why-ar...