the bug is when you /kill @a in the lastes snapshot it broke the whole game you can move and kill but you cant enter any portal , collect any item on the ground , and mobs like cows , pigs , sheeps ... wont responde if you attack them normally they would run but with that bug they dont move
and if you breake any block it willbreake but if you try to get into the hole you made you cant
I have experienced the same issue too. I can't enter any portals, all blocks I punch disappear, and sometimes, blocks will be replaced with netherrack or the block that is in the punched block's coordinates... in the NETHER