Looking at general Google wisdom, the rule seems to be < 50 calories doesn’t break a fasted state, and cinnamon is 20 calories per tbsp, so you should probably be okay as long as it’s a reasonable amount.
That general wisdom seems to be contested though, mostly with the idea that any calories at all will break a fast, but it definitely depends. Ah article I found that at least claims to have been reviewed medically: https://www.mindbodygreen.com/articles/what-actually-breaks-a-fast-according-to-intermittent-fasting-experts