Most of it washed off with water and scrubbing, but there's still a
red stain all over inside that wouldn't come off with gunk or lacquer
thinner. This is definitely not rust.

Is there anything in make-up that can harm concrete?

No, I wasn't making out with the mixer. This thing came from a
cosmetics factory and then sat unused in a warehouse for several
years.

That's right, ladies - your make-up is made in concrete mixers!