for example, there is a recent study related to mask use in bangladesh which is getting an enormous amount of press as supporting mask use. while it does support mask use, that is not the main focus of the study, and furthermore, while there was a 9-11% reduction of spread associated with mask use, the actual numbers involved are quite small, so it is not quite as convincing as one might initially infer.
(i am not against mask use, just against breathless reporting :-).)