A colour change or some other obvious indicator to show when the timer is running would be nice. The text changes and so does the play button but they are very subtle, especially considering how small the widget is on a 4k display. I have attached an example of the approach Time Doctor uses. Any number of alternative approaches might be good. In Time Doctor the task colour changes, the header colour changes, the icon and its colour change, and in the widget the text goes bold and a light turns on to show that the app is 'recording'.