I want to add a couple of good ones I’ve found:
Jeff the Killer lost media: no one knows where the original Jeff The Killer image came from.
Mortis.com: old weird website
Also here’s a good website on various obscure computer/Internet related oddities: https://suricrasia.online/iceberg/
I cannot find a single credible source for the band thing. There is a band called Cicada 3301 but they are completely unrelated. They named themselves after it but do not have any connection or affiliation. I wouldn’t exactly use a Top 10 video as a reputable source.
As for Kryptos, it’s a world famous and unsolved bit of cryptography. If it’s overblown then solve it?