The direct invocation of the original "oil floats on water" incident meme is too much for me. I don't know if the other incidents are as directly inspired as this one, but doing such a clear and obvious nod to that meme without any addition of the author's own content is a massive detriment when the article is already a homage to it.
The ensuing narrative feels hackneyed in extreme and bare-bones. I feel like I've read identical things about a dozen times before, except that previous articles about online media take sufficient care to characterize their protagonist and give them enough exposure to make them stand on their relative own without relying on the pre-existing meme. As-is, this article will feel dated and cringe-y in just a few months, maybe a year.
Again, I feel I need to reiterate just how dependent this article is on the existence of the meme. Its single hook point is SCP-ifying a meme. The only original components the author has provided are the audio files and an extremely simple narrative that could have been expressed in merely one or two sentences. Everything from Addendum 2 forward fails to add to the premise or build something on top of the meme it's using as inspiration, and what is in Addendum 1 is merely a visually-spiced interview log with 3 lines.
6661's dialogue is overtly expository and edgy in a way that makes it difficult to read. I find it hard to believe that the Foundation would simply believe what 6661 is telling them without any resistance or question. For all they know, popularizing the meme could just be giving it more influence and staying power to spread 6661-1 instances. Would it not be more in line with the commonly accepted methodology of the Foundation to simply ensure the meme exits the public consciousness as quickly as possible, most likely reducing its activity or making it adopt different methods of garnering attention?
Maybe your explanation is "that would kill it: the Foundation doesn't kill anomalies without motive" - something like that should be explained within the article. Although not every potential inconsistency or dark spot can be reasonably explained while conserving a decent pacing, at least the very basic motivations and reasonings that drive the narrative forward should be evident.
On another topic, the clinical tone is poor in extreme. Paragraphs like these:
It is theorised that the collective popularity of the Trollface meme created a thoughtform which manifests via the meme. SCP-6661-1 came into existence due to the decline in popularity of the Trollface meme. The irrelevance caused thoughtform to latch onto the darker SCP-6661-1 to garner back attention.
Should have not passed the critique stage. A suggested correction:
It is theorised that the collective popularity of the Trollface meme created an emergent consciousness that manifests via unique iterations of the meme. SCP-6661-1 are a consequence of the gradual decline in popularity of the Trollface meme: in an attempt to sustain itself by regaining popularity, the consciousness resorted to imagery that is darker in tone and direct memetic manipulation.
I'm certain this is not optimal, but I strongly believe the current version is insufficiently detailed and unacceptably difficult to parse. The term "thoughtform", while not strictly non-clinical, is obtuse terminology that is not required to express what is intended.