Single punch to tree destroys block

((I hope this is the right place for this. I am new. Searched the jira for similar issues, but most were the opposite.))

But I walk up to a tree, unarmed (screenshot 1). Left click the mouse. And the tree is destroyed in one click (screenshot 2). This is in creative mode. Same thing happens in survival mode.

This is a fresh download and install of minecraft. No mods. Nothing but what comes out of the box. Not wearing anything
.