I've looked at a lot of COVID related research papers over the last year, which is exactly why I don't take them seriously anymore. The quality is extremely low and they routinely do things that aren't scientifically valid without any obvious repercussions for the authors.

Fortunately, again, one more time. You do not need scientific studies to see the truth here. The goal of mask mandates was to change case curves. That was their only justification. In a large number of places mask mandates were added or removed without the case graphs changing. Therefore, they do not work. Everything beyond that is irrelevant and frequently confused, e.g. studies on masks are not relevant to the question of mask mandates.