Pale gardens naturally generated prior to 24w44a will no longer seem to spawn creakings upon updating the world to 24w44a.

If you load up a world in 1.21.3 and load the chunks of a pale garden, you'll have creakings at night as expected. But if you update to 24w44a in search of resin, the creakings will no longer actually spawn in any of the previously loaded chunks. Chunks loaded for the first time in 24w44a will spawn creakings.

In 1.21.3 I punched a creaking and exposed their creaking heart block; F3 shows it as active. After the update to 24w44a, F3 shows that that same creaking heart block has both 'active' and 'natural' set to false.

HOWEVER. If you break a log beneath the creaking heart and replace it, the block will change to active, and that particular creaking will spawn. The creaking heart will remain marked as not natural, but the player(s) will still be able to spawn the creaking and receive resin.

With further testing, you can cause a creaking heart to become active via block update. So if you flail at side logs in an old pale garden, eventually you may cause a heart to activate and a creaking to spawn on your face. It's currently proving a successful jump scare even in creative, haha.