Any anti labour sentiment tends to coalesce with these protests. Don't treat it as "30% is antivaxers", it's likely to encompass more niche complaints with how the government and other right-leaning causes.
Like a common one I see is Gen-X/older Millennials who are in a decent financial position tend to be against the public health measures because they essentially can't freely travel overseas
Another one is the sentiment that "We're out of touch with the rest of the world, we just need to let it in and deal with it so we can move on" is scarily popular too
The survey literally just asked if people support the mandates then if they support the protest, there wasn't a lot of nuance about specifics there