SCP Foundation

YouTube can be educational¹, and with that being said I was watching a series called the Tale Foundry where in one video, it talks about how H.P. Lovecraft and his "Cthulhu Mythos"² was considered a Mythos, and not a novel or a series of short stories like J.R.R Tolkin or George R. R. Martin.

Here's the Video: Are H.P. Lovecraft's Mythos Actual Myth?

With all of us here, my question is similar: Is the SCP Foundation it's own Mythos/Actual Myth?

Sure. Google says the definition of mythos is

(in literature) a traditional or recurrent narrative theme or plot structure.

so we've got that going on a couple levels. We have traditional themes (security, containment, protection) and a recurrent plot structure (the presentation of stories as clinical documents).

The dictionary doesn't mention it, but I think a set of recognizable characters and forces (preferably larger-than-life) is also an important part of a mythos, and we've obviously got that with our legendary skips and personnel.

Even the secondary non-narrative definition, and the example they chose for it, applies to the spirit of the Foundation:

a set of beliefs or assumptions about something.

"the rhetoric and mythos of science create the comforting image of linear progression toward truth"

I don't think either the Cthulhu Mythos or the Foundationverse count as a mythos. Both the video you linked and the definition state that a mythos is something that's become reflective of a culture. Horror films might be a mythos, if you follow the critical theory that popular horror films reflect societal anxieties.

They call it the Cthulhu "Mythos" because it's about a pantheon of deities and related folklore, which were later codified more directly as such by noted hack August Derleth.

Even if you limit "culture" down to our readership, I don't really see how the invented mythology of the Foundationverse represents our shared values. For example, our values of inclusiveness and representation are reflected in our writing culture and rules, not by any in-universe traits. (I'd be happy to hear counterarguments.)

What we and they (and 1632 and the Man-Kzin wars) have is a shared fictional universe.