I have owned this 2020 keystone outback for almost a year and have only recently seen this seeping through the wall. What could it be?
That looks like the early stages a demonic infestation.
What area is this ? Near a slide ? Have you been up on the roof ? When was the last time you had maintenance done ? What is behind this wall ? Access panel ?
The wall looks wet in places. I imagine water is in your wall, pushing out debris from the nail holes, probably combined with the laminating glue, making it look the way it does.
If it has been very hot where you are, I suggest checking the roof for cracked or melted sealant. Get some dicor if needed and seal it up. Check along the gutter edge closely. The roof material can develop drying and hairline cracks. You can use silicone in this area.
Check window seals, and if you have a slide, lube the seals to keep them working properly.
Lastly, get the wall dry asap. The longer it is wet, the more damage you will see in a day or two.
If that isn’t a damp wall, as it appears to me, I would say it is caused by high temps.
Blood.
Wanted to clarify, it’s a black sticky substance
What does it taste like?
Why is there staples there?
Source: What is this seeping through where the nails are in the wall?
