Why don't you read the study and raise the specific confounders you think are missing?

The answer is universally "no", there's no such thing as "controlling for [all] confounding variables" without blinded randomization. But we unfortunately have to rely on observational studies to try to understand the world. At least to understand what specific questions can justify the cost and complexity of a randomized study.

So yeah, of course there are confounders. Some are controlled in this study and others are not. Which are the important ones you think are missing?