At this point it doesn't matter on the reason, Chrono is just salty that his predictions for Sanji in the past didn't come true.
I can kind of understand him dropping One Piece after Wano, the WCI arc had some issues but the Wano arc was even worse, so him dropping the series after that arc is understandable.
But the way he is now a full on Sanji hater just because his predictions didn't come true, just makes him into a immature brat.
To me it seems like Chrono was never truly a Sanji fan, he just wanted Sanji to be like Zoro, get awesome cool fights and randomly show CoC.
I can understand disliking Sanji before WCI but ever since the WCI arc and the Wano arc, his character has improved a lot, hating on his character after Wano makes no sense.
There are some characters you can like at first but then dislike them later on when that said character is misused and treated horribly by Oda, especially if there is a good chance that they might not come back to the story.
Sanji is not one of those characters.
I don't understand why some Sanji fans sometimes love to bring up Chrono, he has never been a Sanji fan, just a loser posing as one.
He jumped on the Sanji hype train during WCI and then dropped off after Wano when his headcanon for Sanji during that time didn't come true.
He also went from being a decent user to a complete fucking douche now.