Actual (N95/FFP2/FFP3) masks DO work, your comment is misleading. The study you've linked says:

> Colored masks of various construction were handed out free of charge, accompanied by a range of mask-wearing promotional activities inspired by marketing research

"of various construction" is... not very specific.

If you just try to cover your face with a piece of cloth it won't work well. But if you'll use a good mask (N95/FFP2/FFP3), with proper fit [0] then you can decrease the chance of being infected (see e.g. [1])

[0] https://www.mpg.de/17916867/coronavirus-masks-risk-protectio...

[1] https://www.cam.ac.uk/research/news/upgrading-ppe-for-staff-...