This may be a world generation bug. I personally found decent amounts of Ancient Debris in different worlds, so no problem for me. To test if your world has a bug: copy your world, turn cheats on, give yourself a repeating_command_block, go to the nether, and insert the command
execute @a[name=Stephanie] ~~~ fill ~10 ~10 ~10 ~-10 ~-10 ~-10 air 0 replace netherrack
(replace 'Stephanie' with your in-game name) Fly around the nether and see whether or not there actually is Ancient Debris. Even if there's only one or two, this does not mean it's a bug. World generations vary; good luck!
Is this actually a bug? I've seen videos online where the anvil doesn't (or shouldn't) break once it touches the ground... unless there's a torch or slab underneath, it does not make sense for an anvil to break on a solid block.
Need more info ^^ Are you playing on a world before the Nether Update? If so, loaded chunks from older versions may not contain any Ancient Debris. They're also decently rare, try using beds in the nether to make the process of finding them easier!
I don't know why it sent me to BDS. This was meant for Minecraft: Bedrock Edition ^^