I don’t think it’s an unreasonable title, but it’s also not accurate. The paper states quite clearly that they’ve found reasonable evidence of a known biomarker. They don’t know enough to say whether it’s from a biological or some abiotic process (but speculate a little about what that might mean and what evidence they would need to take that further).

That’s quite a different tone from the article, and I think the comments here and elsewhere online reflect that.