I played Survival and then I saw this thing. (in the picture)
When I cut blocks from it the block just disappeared.
Then I left the game and came back and that whole wall was not there.
I think I've seen it already in java edition.
(Sorry if it is not written correctly I use translation)
[media]
This is a Bedrock issue, so you've posted this in the wrong project. See all projects here. However, this has been already reported over at the bedrock project, so this issue duplicates MCPE-55092.