The Bug:

Mineshafts can be generated in the bedrock layer rarely, again. MCPE-147575 is back again, and some new world seeds for this bug were found a few years later.

Example 1:
Seed: 1669320484
Coordinates: -877 -59 778

Example 2:

Seed: 0

Coordinates: 2373 -61 -4062

Steps to Reproduce:

1. Create a world with any of the following seed examples I have given.
2. Do /effect @p night_vision 10000
3. Teleport to the following coordinates based on the seed you used to generate the world.

Expected Results:

Mineshafts must never generate this close to the bedrock layer.

Observed Result:

Part of a mineshaft was generated in the bedrock layer. No bedrock blocks are replaced by the mineshaft.