India vs Bangladesh: Pink Balls Hand-Stitched To Help Aid Reverse Swing: BCCI Official

The pink ball aids conventional swing more than it reverses because of the extra lacquer used to make sure that the ball is easy to spot even under lights.

source https://sports.ndtv.com/india-vs-bangladesh-2019-20/pink-balls-hand-stitched-to-help-aid-reverse-swing-bcci-official-2135160