Teams Meeting Window Resizing Problem

I was using MS Teams for online lectures, all is well until I open the chatbox and the window just resize itself.

Normally the window should look like this, this is normal.

But when I click the chatbox button the upper part just disappeared.

In the following photo, you can see that the upper part of the window is completely gone, with no minimize and close button as well.

Once I type something in the chatbox the window shifted and the chatbox is gone as well.

Can someone please help me get the window to normal? I have never encountered this before, it happened two days ago, and I don't remember tempering the setting myself.