If you charted a timeline of Ben Affleck's time as Batman and plotted the points on it where it's been unclear whether he would be continuing as the character for future movies, you'd have a lot of pins in your map.
Barely a few weeks go by these days without someone wondering whether he's going to pull out of The Batman and any other DCEU movies that have been lined up. And it all tends to come back to his own comments, which tend to stoke the fires of speculation through sheer vagueness.
He's been at it again on the Justice League marketing tour - talking to ExtraTV about what the future holds for him as Batman. He was asked whether he will get to five outings as Batman, with three already in the bank, and his response was a simple "I don’t know about that. We’ll see what the future holds.”
Naturally, that evasiveness has been enough for everyone to now suspect he's unsure on his future. With so much apparent turmoil around The Batman production (before Matt Reeves came on board and rebuilt it from scratch), it wouldn't be all that surprising if Affleck did take the opportunity to leave the role to someone else. He likes his creative freedom, and having to wait around probably isn't his idea of a good time.
Or maybe his evasiveness is just because Batman dies in Justice League or something... Nah, maybe not.