The bug
I'm a lefty player, then, I play with a mouse configured for lefty persons. The main click to the right click, and the secondary click to the left click, but, when I try to place a block, instantly it'll break the block and place it in the same time, also, when I press the secondary click to a mob, it'll hit that mob and interact in the same time, for example, when I press the secondary click to a villager, it'll hit the villager and interact to him.

How to reproduce the bug
1. Press Windows button and go to settings.
2. Go to devices and there, go to mouse
3. There, change the principal click, to "Right"
4. Close it and run "Minecraft for Windows 10"
5. Open a world and pick up a block or search and entity interactable, like a Villager
6. For the block, try to place it; for the villager, try to trade with him.