https://thefederalist.com/2020/11/18/major-study-finds-masks-dont-reduce-covid-19-infection-rates/
Other studies show that 85% of people who got covid wore masks "most or all the time".
https://wwwnc.cdc.gov/eid/article/26/5/19-0994_article
Most of the studies before covid agreed face masks offer almost no protection.