It's easier to see if a frame is maximized, but this is reproducible as long as the lower frame edge is touching the Windows taskbar.
Evaluating the follow code to "toggle" the frame decoration: (set-frame-parameter nil 'undecorated (not (frame-parameter nil 'undecorated)))
You can see that the echo area ends up about 50% hidden under the taskbar.
Before:
After:
