I don't think this PROVES anything, but it is a data point....
My husband and three of our adult kids work together. Their place of employment has only had a few positive cases here and there since this whole thing began. Now that several people there got vaccinated, there has been an explosion of cases. I posted a tweet yesterday asking for studies on this vaccine shedding, and someone who works with my husband messaged me and said that every department where someone got vaccinated now has multiple cases, including some of the vaccinated individuals. I think every single person in my husband’s department is out because of it.
It may not be the vaccine, but how people are interacting with each other when they're vaccinated and feel "safe" to go about gathering.