Swimming out of water with blocks over my head while looking up made me swimming under roof. It's even possible to not move under the roof, as long as I don't look down.
There's been similar bug in the past, but that should be resolved.
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I've thought it'll be duplicate, but couldn't find any relevant similar bug. Even that I knew it is not recent issue.
Thank you for your report!
We're tracking this issue in MCPE-48958, so this ticket is being resolved and linked as a duplicate.
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