I think the reason why it's so easy to spread misinformation (not just about COVID vaccines) is that there's just too many facts out there. It's easy to cherry pick facts without context to support any conclusion whatsoever. Another comment in this thread points out that vaccination typically gives 10,000-100,000 times the antibody needed to fight an infection. So the 5.7-fold vs 8-fold difference is fairly meaningless in the proper context, but it can create doubts wholly disproportionate to its significance.