It was established pretty firmly by the end of 2021 or early 2022. There was even at least one site that gamified it, by showing graphs of infections/deaths for similar US states and similar European countries and having you guess which ones did/didn't do various measures (lockdowns, masks, etc) or having you guess at what point in time they were instituted/repealed. None of it had any effect. IIRC the only real visible patterns involved latitude, time of year, and average population age. It's just really hard for most people to accept just how much their lives were disrupted from lies (if they ever even encountered the truth).
I think a darker possibility also looms: that there is ongoing astroturfing across the internet in defense of what turned out to be ludicrous policies.
In real life, there seem to be so few people who stand by lockdowns in the face of all the data that's now available. Vanishingly few serious epidemiologists continue to contend that lockdowns were helpful. All five of the big five medical schools have published multiple papers concluding that lockdowns were more harmful than helpful.
So what, are these people just chronically online and uninformed? I mean, we're on HN, where there's typically a more informed and data-driven conversation. What makes this topic different?