Pistons can't move blocks that are in lava (I don't know about water). For example: you have a slime block line of 5 slime blocks (that doesn't touch the bottom of the lava lake) and 2 of the 5 slime blocks are in the lava and 3 are not. If you put a piston on the side of one of the slime block above the lava and try to activate it it doesn't activate. (This does work in the previous version) (it's probably because something messed up so that the lava counts for the piston push limit of 12 blocks)

This is version 2 of an report I posted earlier, I thought it was a different version then it actually was and a mod said I needed to make a different report if it also worked on 23w51b and that was the version that I ment in the other report.