They believe the cause is the industrialized use of rat poison for agriculture. The rat poison is dyed blue so humans know to avoid it. These pigs have likely been eating it directly or eating animals who died from it.

It is definitely toxic to humans if this meat is consumed.

That article doesn't have a relevant photo, this one does...

LA Times article (paywalled): https://www.latimes.com/california/story/2025-08-05/exposure-to-rat-poison-turns-meat-of-wild-pigs-blue-authorities-in-monterey-county-warn

Direct link to photo from the article: https://california-times-brightspot.s3.amazonaws.com/fb/d6/705325ab4f518b1d259d1d51f360/me-rodenticide-found-in-wild-pigs-handout-01.JPEG

And yet they couldn't include a photo of one of the blue pigs in the article.