New to me, but did you read their response? It says "The study found that cloth mask wearers had higher rates of infection than even the standard practice control group of health workers" but they say that health care workers should follow guidance.
Would not standard practice be to wear proper masks?
Yes, here we go: "some subjects in the control arm wore surgical masks." And indeed, someone comments "The control arm had less than 1% of no mask use".