Floating bottom bar?
TeraTerm v4.105, Windows 10 Pro 20H2, NVIDIA GTX 770 video card.
The window has a bar floating below the terminal window that is also slightly wider than the terminal window. The Restore/Maximize button on the main window is grayed out. It appears on the floating bar. When maximized, the maximizing stops at the width of the floating bar, since it's wider than the main window. There is transparent space between the main window and this floating bar and also along each side when maximized, since the maximizing stops at the width of the floating bar. The display box in this floating bar shows the IP address that I'm connected to, but it doesn't have room for the full IPv4 address. In general, this bottom bar does not appear to be fully thought out and it looks weird.
Disregard this. I removed TeraTerm and reinstalled without the Collector and the bar wasn't there any longer. So, I'm guessing it had something to do with the collector. However, I still think it looked weird and didn't follow normal Windows conventions.