On Satanic I believe it's an intentional aspect of the fog in that room, it certainly doesn't happen elsewhere.

On The Edge, that's just what happens when items get left under lifts, or in doorways, they get destroyed.

I don't think so man https://www.youtube.com/watch?v=pr0L7bKx_BU :D

well he is lifted above the fog when he stands there?

There are blatant big fat gaps in the floor that are more obvious in that vid.
It must just be coincidence that I've never seen it NOT fall down one of those gaps when I've played on it.

It fell down the massive gaps, yeah.

Since fog is mostly used in death pits, the shader does probably have a nodrop flag on it, causing items to disappear (as they would in a death pit). I'd rather not call this a bug but an overlooked shader flag... happens! :)

In case you don't know your QL history: cityy was also responsible for quad-and-weapon-eating water on 2 maps, so he knows what he's talking about! :)

Not a bug!