I had no idea Toad did that before. This was an unintentional change, due to an intentional change for something else. You can restore old behavior by closing Toad, and adding this under the [SETTINGS] section of Toad.ini:
MainFormOnTaskBar=0
There are some directions here on how to find Toad.ini
I have logged this as a bug in our internal bug tracking system and will hopefully fix for version 14.2.
-John