There is very much plenty of fairly reliable evidence that masks work. And the better the compliance the better they work. In nurse studies you get much better results than in population studies, for instance. Now that I'm looking I'm hard pressed to find any studies that go against this conclusion.

https://jamanetwork.com/journals/jama/fullarticle/2776536

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7191274/

https://onlinelibrary.wiley.com/doi/full/10.1111/jocn.15401

https://bmjopen.bmj.com/content/5/4/e006577