Minecraft: Java Edition is busy testing the upcoming 'Caves and Cliffs Update' through early snapshots.
The latest snapshot, 21w08a, is rolling out now to testers with a ton of smaller tweaks and changes.
This snapshot mostly makes changes to the two previous snapshots, like renaming "grimstone" to "deepslate."
Ore textures are also getting updated, and the way ore is distributed in the world is being tweaked again.
Minecraft: Java Edition is rolling out Snapshot 21w08a to interested testers, and includes a host of tweaks and fixes to the last Minecraft snapshot. All of this is in the name of testing the upcoming Caves and Cliffs Update, which isn't slated to release until Summer 2021.