So, a few months ago I have discovered this bug. I didn't report it because I was actually thinking it will be patched soon, but today I have decided to see if it still works and.. it does.
So, you basically walk off a block ( must be a one block fall so you can build a block directly under yourself), and hold the right mouse button, and you will be scaffolding infinitely. Works both in survival and creative.
I don't think that's a problem on this particular version because, as I said - I have encountered it before.
Thank you for your report!
However, this issue has been closed as Working as Intended.
It's quite hard to tell from the report, but I believe you are describing the feature in Bedrock where you can place blocks at your feet, a feature exclusive to the Bedrock version of Minecraft.
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