My hen has a weird lump on her mid/lower back

[balkflock]

As you can see, it collects a lot of dirt. I’m thinking it might be the oil gland, but I wanted to come on here and make sure it’s nothing serious.

…Ew! Is that a bug on it?

 

[MysteryChicken]

That's the preening/oil gland yes. Completely normal to see on a bird.