I'm just testing this now on my S23U. So, when I replace the S pen the widget continues to show the percentage. But, after a short time the circle will go blank. Now whether that is by design (full charge reached) or a bug I can't say, but it does remain off until such time when i remove the pen. What I can say though is that I can't replicate the same behaviour on my Tab S9U. The circle remains on screen at all times and shows the percentage. Bug?