It looks dirty. (Not exactly a stain)
I wasn't worried about the lubricant I used up to now, but when I switched to LS Bell Hammer / LS Bell Hammer GOLD and operated for a while and confirmed the application site, black particle-like dirt appeared.
Such a condition is called contamination, and occurs when the LS bell hammer/LS bell hammer GOLD modifies the metal surface.
This process is necessary to reduce friction on chains and sprockets.
If you are worried, please wipe it off with a waste cloth.