There's a ton of bad science regarding the effectiveness of masks that people cite claiming it's proof masks work and mandates were justified. Yet when you present them with good science that concludes that masks most likely have no effect, they claim it's not enough.

One of my favorite "bad science" studies on masks that often gets cited is this one from the CDC: https://www.cdc.gov/mmwr/volumes/71/wr/mm7106e1.htm

They even have a nice graphic that shows you the percent increase in safety like it's an RPG and equipping a mask boosts your stats or something. The study itself is complete garbage which is also noted by the tiny barely legible text at the bottom of the image which states "Not statistically significant."