At least according to what he says to The Ring. He's not recovering well from his shoulder injury.
https://www.ringtv.com/642678-gary-russell-jr-still-recovering-from-shoulder-injury-unsure-if-hell-fight-again/
This guy had some of the fastest hands in recent years, he had potential to be great
but he squandered it all fighting his eternal rival TBA over and over again over the years, or not fighting at all