To see the bug ,you can try to summon an ender dragon at Bedrock layer(y:-59—-64).The ender dragon will destroy the blocks.If there is water above,the ender dragon will descent under the all the bedrocks.(One more to say that the ender dragon can not fly under the bedrock from the higher place of the bedrock if there is no water above.I do not know whether it is a bug either. )(If there is water,sometimes the ender dragon can fly back above the bedrock.)The particle effects of water will appear under the ender dragon,not under the bedrocks which are covered by water.

This bug appeared also in 1.20.1.If you need more imformations, I can upload the saves.Thank you very much.