When you place bedrock above one of the new mushrooms and bonemeal the mushroom, it overrides the bedrock to make room for the stem of the giant mushroom.
MCPE-66449
New Mushrooms Break Bedrock Blocks
Resolved
Duplicate
0
Thank you for your report!
We're actually already tracking this issue at MCPE-65661, so I resolved and linked this ticket as a duplicate.
If you would like to add a vote and any extra information to the main ticket it would be appreciated.
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