One of the goals of DC Rebirth is to make the characters more closely resemble their most popular versions. In some cases, that means making a character's physical appearance look more like an adaptational counterpart. last week we discussed Wonder Woman, but Nightwing is another good example.
When most people think of Nightwing, this is what they picture. It debuted in the Nightwing miniseries (1995) that led to him getting an ongoing:
Nightwing kept this costume until the New 52, and whenever Nightwing showed up in a show or video game, he wore a version of this costume. Except, for some reason, the blue part was turned into a bird. Almost every single time.
These are just five examples: The New Batman Adventures, Teen Titans, The Batman, Young Justice, and the Son of Batman trilogy.
In the New 52, beginning in Nightwing #1 (September 2011) to be precise, Nightwing got a new look after almost 20 years:
Then he quit being Nightwing and became a spy, but as part of the course correction - for lack of a better word - of Rebirth, Nightwing showed up in Nightwing: Rebirth #1 (July 2016) looking like this: