Slime blocks can only push entities 5 blocks high instead of 6 blocks high as in 1.15.2

I have a redstone map in 1.15.2 where i create redstone contraptions, and one of the contraption consists in to push me with pistons and slimes blocks, and it push me 6 blocks high (about 6.4 blocks)
I made a backup of this map and now i play it in snapshot release candidate 1 and everything work perfectly exept this contraption because the piston + slime block push me at only 5.9 blocks so i'm blocked in the block
(sorry for frenglish)