The bug
The rotation of for example lily pads changes when updating from 1.12.2.
This may (not tested yet) also affect other "random" models e.g. grass and flowers.
Thanks to Lapisdemon for helping me with this bug report.
Steps to reproduce
Place lily pads in a 1.12.2 world.
Open the world in the latest version/snapshot.
Notice that the rotation of the lily pads changed
Is this issue still valid? Since the time of posting, the game has moved far past these version of the game to still be relevant.