The problem with hypothesizing about connections between Covid/vaccine and cancer is that most of the people who would have gotten cancer in the past year anyway, even if there had been no Covid pandemic or vaccine, have had the vaccine and/or Covid in the recently. So all these people can say "hey, I just got that vaccine, maybe that's why I got cancer." But that doesn't mean anything unless overall rates of cancer have gone up since Covid or since the vaccine. I tried to look this up, but the American Cancer Society's "2021" Cancer report seems to be based on data from 2017. I'm not sure where to find more recent data.

I did have two doses of the vaccine about a year before I was diagnosed with endometrial cancer and a booster about 6 months before. I also had Covid after I was diagnosed. Personally, I don't think there's any connection.