The "milled" section is full of striations that are are all concentric with the pedal. This is what toe strap wear looks like. Toe straps get dirty. The dirt is sand, which is abrasive. The toe strap wears out long before the crank arm, but the toe strap gets replaced. Compare:



Note that the "stronglight" logo is not centered between the pedal and crank holes; it is closer to the pedal. I rather doubt OP's crank has been shortened in any way. It may be a short crank arm, with different proportions than the usual ones, but it has not been intentionally modified. It's just worn out.