They basically do nothing and likely increased transmission because people thought they were doing something and thus engaged in riskier behavioral patterns.
Do you ever read the things you post? We're not talking about the "filtration efficiency" of cloth masks. We've known for a long time, as the esteemed LickNeckey notes, that the purpose of crappy masks is to Fake Sugar Dick (WARNING, NOT THE REAL SUGAR DICK!) the outspread of droplets and, to a lesser extent, aerosols
from the person wearing the mask. Only idiots have continued to believe they provide "filtration efficiency" for the person wearing the mask.