If you think the 2020 election was rigged or that Covid is not real, or that climate change isn't happening, or that the earth is flat, or that the moon is made of cream cheese, chances are you strongly dislike the Wikipedia entries on those subjects and believe it's biased against you.
And these aggrieved parties can find each other online and start workshopping narratives of why their causes were unfairly targeted and propagandized, and from there you're off to the races with uncountably many whackamole narratives that create an increasingly self-sustaining alternative reality where it's just obviously the case that Wikipedia is evil. Which, I think is a symptom of Wiki's success in the face of failed pushes to spread misinformation on it as a platform.
I think fact checking sites had a good heydey from say 2008 to maybe 2016, but a combination of underqualified editors in some cases, Enlightened Centrists who have confused ideas about truth, and Bannon-style propagandists who flood the zone and argue that they are biased, were able to undercut those fact checking sites as a conventionally accepted model of information vetting.
Wikipedia continues to be resilient against those efforts because they have well defined processes for reliable sourcing that are strongly enforced and almost purpose built for a moment like this, so the misinformation campaign can't operate from the inside to the degree that it would like to. It doesn't mean there's no issue with intentional PR campaigns or other campaigns flying under the radar but it feels like a pound of grievance from misinformation spreaders for every ounce of legitimate complaint, banking on people not because able to compare the relative scales of the different categories.