Looking a bit more at the graphs in the study (https://www.healthsystemtracker.org/brief/covid19-and-other-… ) I see that the percentage of deaths among the unvaccinated started off at 86% but steadily declined down to 71% Dec. 2021, and then a more pronounced drop to 58 and 60% Jan and Feb 2022.
I guess that reflects the declining efficacy of the vaccine over time, and then the Omicron variant surging this past winter, with it partial immunity escape due to dozens of mutations in the spike.
It also reflects how the booster shot didn’t get the same uptake as the original shots, leaving a lot of ‘fully vaccinated’ people without the maximum level of protection they could have had.