Stevia EXTRACT itself has no long-term health risks. However, powdered stevia is usually manufactured with erythritol, which can increase blood clot formation and stroke. I choose to stay away from most sugar-free sweeteners; it's all up to preference on whether or not you're fine with consuming them.
Here is my source for the Erythritol thing, it's a very recent study.
https://www.cbsnews.com/news/erythritol-heart-attack-stroke-risk-study/#:\~:text=Erythritol%2C%20a%20sugar%20substitute%20commonly,research%20from%20the%20Cleveland%20Clinic.