That's because keyframes are part of interactions; they're hidden by default, but can be toggled under View, Keyframe Editor, when in interactions mode
You will not see keyframes in pose mode, it's solely built to make static/frozen screenshots. But it shows you everything you can do in interactions mode, actually displaying the list of keybinds while its at it, making it better for beginners / practice, or if you're only after static pictures
Those pink diamonds you see at the bottom in the keyframe editor, are when something is declared (a size, for example), or when something is changed (body inflation, for example). Declarations will not do anything if there is only one of the type in each scene; setting breasts to inflation 0. Having multiple declarations at different times, will make said thing change over time. This is how you build an interaction