Fig1B is quite interesting. It seems like the overall cancer incidence in the non-vaccinated group increases much more slowly in the first 90ish days, but then stabilizes at a similar or very slightly lower rate in the middle of the graph at 180 days. I would not expect any non linear time effect in the control group.

I wonder (pure speculation) if this is because many in the non-vaccinated groups die because of COVID and so don't get a cancer diagnosis?