@holger1405 Honestly, they look like trigger locations (maybe some vfx trigger or bounding zones for the Reapers walking around?) or something that accidentally got marked as visible. I'd have to compare it to the original version to come up with a better guess, but that's unlikely to happen.
I don't think it's just a bad visual transfer of fog vfx or whatever, as they're actually inheriting the skybox. Super unlikely to be intentional (if it is, they achieved disastrous results for whatever it is they're trying to do).
Here's a couple images from the original ME3 to compare to
Turns out they're 2D props that bound the level (to make it look bigger than it is). They're just oval planes with a texture slapped on.
Obviously something they accidentally screwed up when they were updating the assets. Hopefully something that can be fixed without much effort ('cause that's probably the only way this ever gets fixed).
