The particle whatsits floating in the air?

Well, regardless, it would be more recommendable to have the material packed into the map file, if possible. It's not always good to make players manually download and place an external material crucial to the map, unless there's a specific reason why you can't pack it.

And I've known VIDE to make mistakes with its automatic process before, so sometimes you have to manually pack the custom content to make sure it actually does get packed in there. Checks and double-checks.

It's called sky27, made for CSS

https://gamebanana.com/textures/3036

It's not my map--you can find it over here.
https://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=1460494504

by the way what sky is that?

lmao what a lovely place