The bug
When a player dies near a sculk catalyst, the experience dropped by the player causes sculk blocks to be created. However, @unknown said in a tweet that player deaths shouldn't cause sculk to spread.
That makes sense to me in two ways. First, the xp a player has is not innate to them, they collected it, in contrast to them dropping from mob deaths. Second, it doesn't make sense for Mojang to intentionally make dying useful outside of it's organic features (teleporting to your spawn point and restoring your health and hunger). Though of course, the decision is up to Mojang.
Steps to reproduce
Obtain some xp
Die near a sculk catalyst
Video
Attachments
Comments 3
It should also be noted that this only occurs if the keepInventory gamerule is set to false. If it's true, then the player retains the experience levels and no new sculk is created.
I found the tweet that you mentioned and edited the description a bit.