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: