Thanks for the question John.
I have been researching fasting for a few years now, but this is the source I pulled from https://www.healthline.com/health/what-breaks-a-fast#supplements
I will say, however, that everyone's body is different when fasting. When you read the Healthline article you'll see that some things "might" break a fast for some people, while for others, they may not.
Speaking for myself, I do not want to take the risk of breaking my fast with a sweetner. Lastly. there are medically supervised fasts where you can likely learn more about what causes a metabolic response for you.
Here's some additional reading for you about fasting and sweeteners: https://www.zerofasting.com/which-sweeteners-break-your-fast/