I think it's a little of everythung under the sun.

I've seen people just going "dunno what's in it" to "5G is controlling you!" to "something something racist." Boatloads of uncertainty and targeted fear, misapplied skepticism, political identity, pseudo science, and more coming together.

In the circles of extended friends I have I've seen doctors (some are 'doctors' but there are real doctors in these from what I can research) holding health conferences discouraging the vaccine and focusing on healthy living and such.

I've also seen people on FB anecdotally showing their mom's fluid buildup and weakness which occured "after the vaccine" as proof of vaccine injury. The thread then filled with their friends showing their rashes and sores they have spontaneously gotten since getting the vaccine. And of course all the doctors they're talking to at the ER and clinics only offer BS non-explanations. Amusingly enough the FB person who started this thread is named Karen.