When I was playing SkyBlock, I found that I can still build a bridge to sand island with no sneak and I was on the center of the block where I place that block. And I report this because this feature isn't removed.
To find bug:
1. Make a 1x1x1 block in the sky.
2. Try to place blocks with no sneak and on the center of the block.
Bug found!
This is not a bug. Sneeking only makes you not fall, have nothing to deal with placing blocks.