Ah, I misread your original post. I thought you were talking about the official recommendations being wrong and then changing. The "general public shouldn't wear masks" is one example where the guidance changed, but I'd argue that overall it's been relatively consistent.
If you are just looking for random people on the Internet being wrong, then yes, there are lots of examples of that!
Re:Cloth masks do protect the wearer
by renewiltord on Monday August 31, 2020 @08:45PM
(#24337386)
Well, it started with the officials because let's just say we're not working with very good raw material here. It's like the tar sands, you know. We have the tar sands, some other guys have shale, and some others have some delicious light crude.
0: https://news.ycombinator.com/item?id=22777170 (claims that training is required or you're going to get rekt, read thread)
1: https://news.ycombinator.com/item?id=22776396 (while doesn't claim a no-threshold model, the threshold is a hundred viral particles)
2: https://news.ycombinator.com/item?id=22735235
3: https://news.ycombinator.com/item?id=22734656
4: https://news.ycombinator.com/item?id=22734923
5: https://twitter.com/WHOWPRO/status/1243171683067777024?s=20 (the WHO saying not to wear a mask, by the way)
6: https://news.ycombinator.com/item?id=22530340
7: https://news.ycombinator.com/item?id=22610180
8: https://news.ycombinator.com/item?id=22595955
9: https://news.ycombinator.com/item?id=22559272
10: https://news.ycombinator.com/item?id=22528527
11: https://news.ycombinator.com/item?id=22529273