I call BS. I read the article in the NYT that gave greater detail.

https://www.nytimes.com/2021/06/19/style/subway-tuna-sandwich-lawsuit.html

And, key words:

“No amplifiable tuna DNA was present in the sample and so we obtained no amplification products from the DNA,” the email read. “Therefore, we cannot identify the species.”

The spokesman from the lab offered a bit of analysis. “There’s two conclusions,” he said. “One, it’s so heavily processed that whatever we could pull out, we couldn’t make an identification. Or we got some and there’s just nothing there that’s tuna.” (Subway declined to comment on the lab results.)

To be fair, when Inside Edition sent samples from three Subway locations in Queens out for testing earlier this year, the lab found that the specimens were, indeed, tuna.

More clickbait bullshit - and from a major news outlet.