By default your Kindara chart is set to fertile peaks, meaning the more cervical fluid you enter, the higher your bars will display on your chart (same with menstruation).
Additionally, we have a fertile valley setting. With fertile valleys enabled, think "High and Dry" - The higher the cervical fluid bars are, the drier, and less fertile the cervical fluid.
With fertile valleys enabled, the lower and darker pink the bars go, think of it like dipping down into the "Sea of Fertility" the higher the water content of the CF, the closer to ovulation a woman is.
Once the temperature spikes, the CF bars should go up also, allowing you to visually confirm ovulation by using BOTH of your primary fertility signs instead of just temperature.
The Menstruation bars follow the same pattern, the lighter the flow, the higher the bars, so that's why you're seeing the "heavy" days have bars that are lower than the "light" days. You can think of it like if something is heavy, it would sink to the bottom.
Whether you enable fertile peaks or fertile valleys is up to you! To update how your chart is displayed go to the settings section of the app and toggle "chart has fertile valley."