Sample rate is not shown by default in the Animation window in 2020.1.0a11.
This is probably very puzzling to anyone who is not used to look everywhere when something is missing in Unity.
Please, make it enabled by default, thanks! 
It’s an editor preference and selecting “Show Sample Rate” will register your choice for all Unity versions thereafter.
My point is that it should be pre-selected by default so that nobody thinks that it’s not there at all.