While updating ViaVersion/ViaBackwards to support the latest snapshot, I noticed that the default handling of the goat horn instrument is quite broken. 1.20.4 used to check if an instrument is present, and if not, it just sets the first instrument from the registry as default. Since 24w09a, this behaviour seems to be broken, when using /give to get an goat_horn, no sound is playing because the default INSTRUMENT component isn't being set. I wonder if this is intended behaviour or an issue.

Here the list of item components of the goat_horn when using /give:

Here the same when using the creative inventory:

Here the 1.20.4 nbt handling: