Other open Unity windows increase in size when entering playmode or the enhancer sidebar is enabled
Version: Unity 2019.3.10f1
I usually work with two unity windows open, One is my main window, the other on my second desktop with my console, animator, and another inspector.
It seems that When I have the enhancer Sidebar open, every time I start play mode the second window gets a little bigger.

After disabling the sidebar and reenabling it. Note the increased height of window.

Interesting. Can you please post a picture of your whole desktop with the two windows? I need to see what is the exact layout of the docked windows in each one. It would be useful to me in order to reproduce the issue here. Thanks.
Here it is in a fresh default project without any of my editor plugins in 2019.4

It seems like it still happens so hopefully it's reproducible on your end.
Edit: It looks like it increases in size roughly the height of tab area on the top of the second window if that's related.