The company that developed cocos2d-x seems to only focus on Cocos Creator. The cocos2d-x github repository did not get any updates since 2021. The check-out of the git repository does not work anymore because the links to the sub-repos can't be pulled from github. There are more than 199 pull requests open... and nobody cares about it at all. The download on the cocos homepage requires Python 2 which is also not supported anymore...
So - from this point of view: Yes, it's dead.
This is quite sad, we've supported cocos2d since 2010 with TexturePacker. In fact, cocos2d was the reason why we've created it in the first place.
But... it's a good game engine that really works well. It has a robust and useful set of features — and it's open source.
The good thing about that is, that there's already an actively developed cocos2d-x fork called Axmol Engine.