I'm running a private server with a lot of mods, and recently these pink dots have started appearing on certain blocks. I can't tell if this is intentional or a bug of some kind.
Here are the mod folders in my worldmods directory:
Can´t tell you which mod causes it but how I would try to find it.
Search for all texture files in your mod and go through them based on thumbnail and name to find that dot texture.
Just be aware that the dot texture could have for example a white dot that gets colored later by minetest
Thank you Skamiz (ki'e do). Sadly it does say it's 'default:stone', so probably a bug.
Looking at every texture is probably the only way, like Bla suggests.
Bummer, but I'm already used to it at this point :)
Since we know it's default:stone now, maybe we can work out what is causing the texture to be different? As far as I know it must be one of these:
The server has a texture pack installed. You would know if you installed/created a texture pack. The texture pack would override stone's texture OR override just the texture of that node, and it would apply to all instances of that node. Also I can see the same pink dot is on that cobblestone in your OP.
A mod is overriding the definition of stone to add a pink dot texture on top. You should search your mod directory for minetest.override_item("default:stone" and similar strings (using grep or similar tools).
Your copy of Minetest Game has modified files. This is easy to detect if you cloned it over git, and quite hard if you installed from a zip/tar.gz download.