The BBC article Soyuz space capsule brings ISS crew back after five month mission describes the return of ISS Expedition 55's "Russian Anton Shkaplerov, American Scott Tingle and Japan's Norishige Kanai" today. Looking at the capsule in this photo from the article, there's a pronounced angled line that separates blackened areas from lighter-colored areas on the Soyuz reentry capsule.
I'm guessing this has something to do with soot produced by the ablation heat shield and a tilted attitude during reentry.
Which direction does the capsule tilt? Does the heat shield point slightly downward with respect to the reentry trajectory to make more lift? Does that result in the blackened areas on the nadir-facing side of the capsule?