I was trying to collect every music disc in the game on my realm. I had previously been hitting the creepers to get them to low health and letting skeletons finish them off to get discs.  I collected most of them this way. Since the release of 1.17.30, they aren't dropping music discs anymore. I've even tried letting skeletons get every shot on the creeper until its death to see if maybe the player hitting it was an issue but it didn't work either. There's nothing in the information about the update mentioning this being a change, so I'm assuming this is a bug.