Disclaimer: I'm happy to comment, but I might note that - because I've commented on anti-vax propaganda in the past - I've discovered that the one thing Saiditors seem to agree on is their distrust of the vaccines, masks, COVID19 &c, and they especially distrust me when I argue that vaccines are safe and masks are important. So, no one here really wants to hear my argumemts against anti-vax propaganda, which is funded by billionaires and has only helped increase the wealth of billionairs. Those who believe the anti-vax propaganda are helping these billionairs, but don't seem to know it.

Now to an answer to your question:

I am a centrist, rather than a liberal, so this might not be the liberal answer you want.

Facebook's and Istagram's policies are to reduce the spread of misinformation and disinformation on its platforms. As private companies, they can and should do this, because the anti-vax propaganda is spreading lies that influence people who don't know that these are lies, and who continue to spread the virus and create violent incidents and vote for corrupt politicians who also spread lies - all on the behalf of their billionaire sponsors. It's a vicious cycle that can be reduced when the social media companies refuse to spread lies. Churches and other websites will however continue their anti-vax campaigns. They do not help the 99%. They only help the super-wealthy.

Project Veritas still has the right to spread misinformation and disinformation here: https://www.projectveritas.com

Antivaxxers will know to visit their favorite videos at that website and do not require Facebook or Instagram as their propaganda outlets, though these outlets and Twitter &c will continue to help spread anti-vax lies. One can look to many relatively new resources (past few years) for their focus on lies on all social media. Facebook &c cannot keep up with them. Some of them are at /s/ShitpostNews, though this too is a remarkably short list.

Do Project Veritas and similar very well funded anti-vax propaganda companies and anti-vax churches and anti-mask political rallies cause harm? Absolutely. They're helping kill off small businesses and jobs by extending the lockdowns and restrictions. They're also harming and killing people, by spreading COVID19, with the help of lies. From a Christian point of view: will these people go to Hell for telling lies? I woud think so. From a scientific point of view: are these people anti-science. Yes. From a community point of view: are they harming the community? Yes. From a political point of view: are they supporting the spreading of lies in politics and thus authoritarian candidates who will enact laws that fleece the 99% of money and their rights? Yes.