Right from the jump I'm skeptical because this is a contagion skip published in the middle of a global pandemic. That is almost certainly going to be viewed as being in poor taste. But I'll give it a fair shake.
and range from mammalian, insectoid, and cephalopodian in physical appearance.
When you go from something, you go "to" another thing or it feels odd. I'd recommend "wide range such as" or some similar phrase.
and lasts can only last outside of a host for 30 minutes before expiring
Oop. extra word there.
The only people with immunity to SCP-5350-A growth are those who have either vegetarian or vegan diets.
This connection feels somewhat preachy to me. Feels tacked-on. Did in the ConProcs, too. I'll hold judgement until I can tell where you're going with it, though.
The Picture.
So, it started me off thinking "how would the Foundation let it get that far?", then thinking about the scope of the problem:
Due to wide consumption of meat contaminated with SCP-5350 before the Foundation was fully aware of the anomaly, a significant portion of the population had been infected.
How could they not miss it? They'd have to clean it up, though. How would they -
A joint action between the Foundation, World Parahealth Organization (WPO), Manna Charitable Foundation (MCF), and Unusual Incidents Unit (UIU) was organized to stop the spread of SCP-5350.
And that's what makes it work. You cashed the check your ConProcs wrote. Scale is a really important thing in Storytelling and it's well managed here.
<Begin Log>
During introduction the prose is a bit hard going. Comes off robotic and unnatural. But after that this is all fine. Good, productive, compelling information delivered by characters that were fairly well developed. Well done, I enjoyed myself.
With animals, there's more than meets the eye.
Are We Cool Yet?
Eeesh. I'm conflicted about the resolution. It seems unrealized, missing its full potential somehow. I mean, this is an anartist, right? And this project of theirs was huge. There should be more than a couple of lines on a sheet of paper. I'm expecting some weird avante-garde shit. You could show more about who she is through her art along with the viral attack.