The bug
If you place a piston and a frog next to it and push the lever, he goes up above the block like he jumped. however, using any other 1 block tall mob that can fit there won't jump and will suffocate and die. I don't know if this is a bug, but it is different behavior that could be important later, and I didn't see anyone else talking about this. also going 2 blocks under doesn't work. Frogs still suffocate.
Affected mobs
Frog
Enderman
Axolotl
Dolphin
Drowned
Llama/Trader Llama
Can confirm. Additionally, after some testing, I found that this is also the case for:
-Endermen
-Axolotls
-Dolphins
-Drowneds
-Llamas/Trader Llamas