Nether gold ore uses the same sounds as stone instead of Netherrack sounds or the same sounds as nether quartz ore.
Nether gold ore makes regular stone sounds
Different sound between Netherracks and Nether Gold Ores
Nether Gold ore has default stone breaking sound instead of the new Netherrack breaking sound.
Nether gold uses stone, not nether_ores sound
Magma block sounds have not been updated to the new sounds of nether blocks
Blackstone uses stone sound effects