Timm said she was going to be killed by Solomon Grundy after he drags her off. Tucker wanted to bring her back, but Timm insisted on leaving her dead. But she was shown alive being lead away by the police at the end of the episode, which was the animation error. His quote is at the bottom of this DC animated wiki, though the link for the source seems to be old:
https://dcau.fandom.com/wiki/Cheetah
"
It was a mistake — she was supposed to be dead — the implication being that Grundy '[pulled] a Lenny' on her.
Well, my co-producer James Tucker kept saying we should bring her back, [and] I kept saying, 'No, she's dead, she has ceased to be, she is an ex-Cheetah,' and, lo and behold, someone pointed out that she was in the paddy wagon — all in one piece, apparently still breathing — at the end of "Injustice for All". D'oh!
So, James got his wish: she'll be back in Justice League Unlimited. Don't know how she got away from Grundy, though."
I would think it would be believable for someone who regularly takes punches from Wonder Woman to be able to get away from Grundy, but they also missed the memo that she was a demigod archaeologist, not an animal gene splicer or whatever that nonsense was, so perhaps it's not surprising.