Seems sadistic to bring back a species to a world in which it can't survive in the wild. It's existence will be nothing more than a plaything for humans to look and gawk at.
The question is different when it can be summed up as "to be or not to be", but I think it's still an ethical bag of hurts.
But for that, you need quality breeding stock in zoos in the first place.
[1] https://defenders.org/blog/2020/03/we-were-wrong-about-wolve...
https://www.doc.govt.nz/news/media-releases/2016/predator-fr...