I had upgraded my world to the newest snapshot, 20w17a. When I was digging for a long time in the nether hoping to get netherite I was suprised I didn't find any. So I did a copy of the world and ran commands to see if there were any ancient debris. I found that there were no ancient debris anywhere.

I downgraded that world to 20w16a, everything I had built on that world (world copy) were deleted. In the nether, soul biome had generated instead of the nether wastes biome in the downgraded version and ancient debris was there.

I guess I have to wait for a new snapshot.