I have hair blocks set to copy the X and Z rotations of the head, and the Y rotation set to 180 so that the hair always points downwards. This functions in 1.19 as intended, but loading the exact same model into 1.18 makes it no longer work. I also made a small test model in 1.18 and that again did not work.

Couldn't reproduce it with the latest versions 0.6.8a