Changing view position in time field (Animation window) on press Play

2) How can we reproduce it using the example you attached

1 Create new project
2 Create cube
3 Open "Animation:" window and choose cube in the Hierarchy
4 See the Animation window - image step1
5 Press play scene (main Play - not in animation window) and see the Animation window - the bottom bar became shorter and the time position has changed (image step2)

If you repeat pressing Play - this bar will change length each time