I see after every explosion of something a red basic texture around the crater. Is that normal?

That is because of some engine changes involving ground-scars. They are fixed in the latest test version, or if it really bothers you, you can turn them off by setting ground decals to 0 in spring settings.

The engine used to use red channel as transparency for scars.
Now it use the alpha channel.

Mod therefore need to update their scars textures.

not the full story.

The default groundscars were bmps and those don't have an alpha channel, so they used the red channel as alpha & the green as brightness (blue was unused).
But there was no reason to use such a limit for all other image formats (with a seperate alpha channel), so now it doesn't transform this image for all non-bmps. (afaik just CA used non-bmps for the groundscars)
Also I commited the new much more detailed groundscars 5mins after the release of 79, so just blame the other CA devs that there is no new stable yet.

Wait wait.. you can make stable too! :) Just add comment "STABLE"!

I asked to do so, but det said I shouldn't.

Also I can't build test's my self atm (my homeserver gets finally a home-made wooden case ^^), so I can't decide if a current repo is `stable`.

Speaking of the new ground scars jK, I don't really like the way they overlap. The fading dirt around the black scar doesn't look right when it overlaps the black part of another scar.

Ok, i tested a newer test version and everything works. Thanks for help^^
I┬┤m noob with Spring...