In my opinion, there should be a separate Yellow button for canceling the Sleeptimer (only displayed when the Sleeptimer is activated). The Blue button should be kept only for activating/reactivating the Sleeptimer (displayed only when the option is not "disabled"). It is truly nonsensical for the user to first have to set the option to "disabled" in order to cancel the Sleeptimer with Blue. The user will be able to reactivate the timer with the Blue button and stop the timer at any time with the Yellow button, without having to change the setting option.
I will see on it...
Edit: PR for it is created