There were lots of good examples during COVID. Remember that you don't need to wear masks, because washing your hands is enough (and we need to save the masks for doctors, but we're afraid to say that, because it will cause a run on masks). Remember that staying 6 feet apart is a magic distance over which COVID cannot cross (or maybe 1 meter, truth depends on the country you live in). Remember that you can't eat inside a restaurant, but you can eat outside, and it's okay for the restaurant to build partial walls around their outdoor spaces to make them more comfortable. Remember that COVID definitely could not have come from a lab leak, and it's racist to even suggest it might have happened. Never mind that the scientist who started the anti-lab-leak open letter was himself heavily funded for GoF research, and he refused to sign his own letter for political reasons.

I don't claim to know the answers to all of the questions (and I certainly don't know where COVID came from), but clearly there are plenty of cases where dubious statements were strongly enshrined as "True" in a way that required major online players to suppress alternative beliefs as "False".