The bug
/stopsound has two success feedback messages:
commands.stopsound.success: "Stopped sound <sound> for <player>"commands.stopsound.success.all: "Stopped all sounds for <player>"
/stopsound has an optional sound argument. When provided, it correctly stops the given sound, but gives the "stopped all sounds" message. When excluded, it correctly stops all sounds, but gives a broken "stopped sound for player" message with the sound parameter blank.
How to reproduce
1. /stopsound @a
→ ❌ It says "Stopped sound for <you>"
Notice the two spaces between the two words, the sound argument is supposed to go here, but there isn't one because this is the wrong message.
2. /stopsound @a random.explode
→ ❌ It says "Stopped all sounds for <you>"
That's not right, it only stopped explosion sounds.
This isn't fixed on 1.16.221 though