We know that he lost his belt on the scale because he didn't make the weight in their fight, 115 lbs and was over the limit and even weight as high as super bantamweight. He cited though, that he has go to thru a lot emotionally and so another case of mental issues. And so before it blows up, he just decided to retire for good.
https://www.boxing247.com/boxing-news/joshua-franco-announces-shock-retirement-at-age-27/265240
Well, that's an unexpected news because I thought that after the loss, he will be more dedicated to try and bounce back in the next division as his weight is not already suitable in his present division.
He still has a future in the industry if he chose to continue as he is still young to consider an early retirement because he could definitely bring a lot more money in his pockets for fighting a couple more in the future and who knows, he might be cut for something at 118.
Anyway, it's best to understand his decision because we are not on his shoes.