As New York magazine’s David Zweig noted, the CDC's findings “cast doubt on the impact of many of the most common mitigation measures in American schools.”Nevertheless, the mask wars appear to be just heating up.
As inconsistent as study results have been regarding masks, I have a hard time understanding the vehemence with which some people demand they be required. This study showed that there was no statistical difference in COVID transmission in schools that required masks vs. schools which made them optional. Oddly, it did show that either of these policies improved over no policy at all.
I say "oddly" only because more broad real-world studies in larger populations with mask mandates have shown that they make no statistical difference with regards to COVID or other viruses such as the flu. Other studies done in labs indicate that masks generally block a significant number of potentially virus carrying particles.
Like I said, studies have been inconsistent at the very best. At the end of the day, if you want to have a chance of protecting yourself with a mask, then buy high quality N95 rated masks, wear them correctly, and follow other guidelines like not touching your face and washing your hands frequently. Most cloth coverings seem to be worse than useless and paper disposable masks not generally much better. Worrying about and trying to dictate what others do accomplishes little or nothing except bad feelings and ill will.