A lot of it has to do with the lies and the cover ups by the Biden administration over vaccine adverse reactions and effectiveness.
Overall, the vaccines were a good thing. However, while the vaccines usually helped decrease the severity of symptoms, Americans were led to believe that the vaccines stopped the spread of Covid, which is a flat out lie. They didn't. While unvaccinated Americans had to watch sports on TV because they weren't allowed in the venue, vaccinated Americans were allowed into 80,000 seat stadiums, spreading Covid all over the place, including coming home to their friends and relatives and co-workers.
Ever watch those drug ads on TV where they tell you about every single one of the possible side effects and reactions, up to and including deaths? But, when it comes to vaccines, not one side effect, reaction, or the possibility of death are even mentioned. Not one. Instead, we have some public service announcement from the government or some celebrity pushing for us to get vaccinated and not one adverse reaction is even mentioned, as if there were none.