Acetylation reaction

In the Friedel - Crafts acetylation of bromobenzene, how is it possible to obtain a black-coloured product?

When the acetic anhydride was slowly added to the reactants - $\ce{AlCl3}$, DCM, bromobenzene - a small, hard, yellow lump formed.

Would this be $\ce{AlCl3}$?

When the acetic anhydride was added, the reflux was initiated. The lump appeared to disappear, leaving behind a dark red solution.

However, when the reflux was turned off, the solution appeared black. I'm trying to think of potential products, such as ortho and para bromobenzene or acetic acid or $\ce{Al(OH)3}$ but why so black?

Does anyone have any ideas?