The bug
The sculk shrieker is intended to be unobtainable as an item as per the resolution of MC-249125. As such, it should have the magenta "Epic" rarity, however it currently does not.
How to reproduce
Obtain a sculk shrieker from the Creative inventory
Mouse over it
Expected results
It would have a magenta name.
Actual results
It is white.
Just want to point out that some other blocks which fall in this category were tracked on MC-227911, which was resolved as invalid.