SCP Foundation

SCP-XXXX designates as 13 WW2 British trench coats.

That is badly phrased. I would replace it with:

SCP-XXXX is the collective designation for 13 WW2 era British trench coats.

That sounds better.

SCP-XXXX is still capable of being torn and dismantled, however, SCP-XXXX seems to completely ignore liquid.

That sounds wrong, particularly the 'still'. That indicates that it is protected from some other form of damage, and you have not said that. I'm assuming artifact of deleted text. And when you say completely ignore liquid, what exactly do you mean? If you mean that it is waterproof and that drops of water slide off e.g lotus leaves, that means it is hydrophobic. Also, the first footnote is both not needed and wrong. Water and H2O are the same thing. Water is just another name for H2O.

Being able to not soak whatsoever. SCP-XXXX appears to still have a manufacturer on the back of SCP-XXXX instances, named "████████". A relatively popular designer in 193█.

Okay, the first sentence is weird. I'm assuming you mean that the fact that it is waterproof has preserved a manufacturing tag, but you've phrased in an odd way. A better way to say it would be:

SCP-XXXX's waterproof nature has preserved it, and a manufacturing tag reading ████████ is visible on the back.

That sounds much better.

and is; the following:

I would say "meets the following criteria."

Is out of view of any individual

I would say "No other humans can see the subject"

Worn during any form of weather, that includes water.

…What does this even mean? You have to wear it during any form of weather, including 'water'. You don't need to say that any more than you need to say that it must be worn anywhere. It is irrelevant. Once you get rid of that, it just says you need to wear it, which you have already stated above. I would get rid of it.

Subject must've worn SCP-XXXX prior to the anomalous event for at least 4 hours in total.

I would replace this with: "The subject must have been wearing SCP-XXXX for at least four hours."

After these trigger-events have successfully complied

That really doesn't work. You could just say "after the above criteria have been met".

pass out into a comatose state

I would just say "enter a comatose state"

Leaving with dead plants, mouldy food3 and even skeletal remains of humans.

I would say: ", littered with dead plants, rotten food, and skeletal remains of humans."

Subjects reported that as if the entire world has been converted into this state after exploring out of the area. Reporting, that buildings seem to be non-existent.

Let me just replace that:

Sucjects report that the entire world has been transformed into this state, with most buildings gone for unknown reasons.

OKay, I'm going to have to give up on the line by line here

You really do need to work on your grammar. Read your article, and anything that sounds weird, change. Do this at least once or twice before asking for more feedback.

Regarding the concept, it seems very similar to that series one gas mask dimension thing, don't remember the designation.

The article also goes on and on about a relatively simple concept, ending with a massive and misused footnote. I would highly, highly reccomend getting the concept checked in the ideas and brainstorming forum. If nobody responds, go ahead and ask in #site19 or #thecritters.