This change has been in there since Cocos2d-x v3.14, released on Jan 3, 2017, so it’s not something recent. It may not be a good idea for stretch to be changed back to “false”, because it seems like this is the first reported issue with this behavior, and there have been many releases after it was introduced, so changing it back may affect all products released since v3.14.
The correct behavior should be dictated by the typical (ie, most common) use case for setContentSize(). The two options here are:
(1) Sprite scales to the content size
(2) Sprite canvas size changes without scaling texture
Perhaps there should have been a request for feedback regarding this change before it was introduced in v3.14, but given that it’s been in there for the past 2+ years, and many releases, along with the fact that there haven’t been any other posts regarding this implementation, it may be best to leave it as is.