By default your Kindara chart is set to Fertile Peaks, meaning the more cervical mucus data you enter in the Data entry page, the higher the cervical mucus bars will display on your chart in the Chart page (same with menstruation).
Additionally, we have a Fertile Valley setting. With Fertile Valley settings enabled, think "High and Dry" - The higher the cervical mucus bars show on your chart, the drier, and less fertile the cervical mucus.
With the Fertile Valley settings enabled, the lower and darker pink the cervical mucus bars show on your chart. Think of it like dipping down into the "Sea of Fertility", the increase in water content of the cervical mucus, indicates approaching ovulation.
When the Fertile Valley option is selected, once the temperature spikes on the chart, the cervical mucus bars should go up. 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 when the Fertile Valley option is used, the lighter the flow, the higher the bars, so that's why you're seeing "heavy" days displayed as bars that are lower than the "light" days. You can think of it as if something is heavy, it would sink to the bottom.
Whether you enable Fertile Peaks or Fertile Valleys is up to you! To choose between Fertile Peaks or Fertile Valley go to the Settings section of the Kindara app found in Menu, select either one in the Chart Style section.