The ink smears are usually very dark green almost black. These errors are often faked. I guess there could be a black smear too. It doesn't look very black.
I'm not saying the note is fake. I am saying this is one of the most faked currency errors. As for the ink smear, I don't believe it came from the BEP, but came after.
It looks like PPD (is Post Printing Damage a term? ). Seriously, it looks like an ink smear from a cheap pen. Your note has seen a lot of circulation, which provides lots of opportunities to pick up errant ink stains. As others have said, it's a spender