One of the articles references the dogs being possibly mixed with chow chow due to black spots, but purebred GSD can have black spots on their tongue.
Our rescue has a few German shepherds that have black spots on their tongues. Sometimes backyard breeders kill the puppies because of it as it is not a desirable trait among GSDs.
Our rescue brought back 21 dogs in total over the past two days. All of them were well fed, dirty, matted, friendly but undisciplined, and outwardly in good health.
They appear to be pure GSDs except for one chihuahua (also saved by our rescue). They may have been mistaken for mixes due to their unkempt condition.
They will go to the vet for checkups and spay/neuter after their cleanup.