Science is hard, and that's why science rarely gives black-and-white answers. This study is not the one final word on the matter. But that doesn't mean it's not still useful.
Science is done based on the evidence that is found, and this counts as some evidence. Does it answer every question? Of course not. Does it help improve our understanding of the occurrence of it? Yes.
Correlation is not causation, but where there's smoke, there's often a fire—as these findings continue to be validated (and there have been other studies that find similar links), it becomes more and more relevant to understand why there is such a correlation—to find a causal mechanism, if it exists, or to confirm that it's just spurious correlation.
Actually, as the replication crises shows, most smoke from papers either isn't real / doesn't point to a fire. So that maybe is a flawed line of reasoning. Correlation (if the research is done carefully to avoid intentional or unintentional p-hacking, and free of fraud) can point to maybe do a follow-up study (or do lots of different kinds of studies to do a good meta analysis that can try to establish causation) but the replication crisis indicates the good studies are swamped by the meaningless ones.
Science is done based on the evidence that is found, and this counts as some evidence. Does it answer every question? Of course not. Does it help improve our understanding of the occurrence of it? Yes.
Correlation is not causation, but where there's smoke, there's often a fire—as these findings continue to be validated (and there have been other studies that find similar links), it becomes more and more relevant to understand why there is such a correlation—to find a causal mechanism, if it exists, or to confirm that it's just spurious correlation.