High levels of haste don't fully break blocks

If you have a high level of haste, around 20, then break a block in survival, it can stick around for a fraction of a second, sometimes you can even break the block again and wear out a tool unnecessarily.
Best example:
Give yourself haste 21 with /effect @p haste 60 20 true
grab a diamond pickaxe and break a piece of obsidian. It will hang for about a second before dropping.