I dont know if its really a bug, but it seems that the /playsound command changed its behaviour.
Pre 25b i could place a commandblock with

/playsound <sound> @p ~ ~ ~

which played the sound relatively to the nearest player.
Since this update i hear nothing anymore when i go to far away and trigger the block. When i look into the commandblock it says that no player was found.

I assume that the commandblock now uses the relative coordinates from "itself" .