"Net Calories" or "Calories (Net)" does not seem accurate with Fitbit wearable integration

If I add this chart for "Net calories" or "Calories (Net)," it appears to show a variable deficit graphing of calories between peaks of -1300 kcal, and -52 kcal, for 8 straight weeks.

I use an integrated Fitbit, and this chart does not seem accurate. It shows a "negative balance" for 8 weeks, but my weight has been creeping up by 1.5% in that same time.

I assume this chart is calculated based on my "energy target/deficit" (which is set to LOSE 1lb a week, or -498.95 kcal) mixed with my total daily calorie consumption.

My calories consumed and burned varies a lot based on some relatively intense exercise that is imported from Fitbit.

Why is this chart telling me I am at a consistent caloric deficit, averaging around -675 kcals, over 8 weeks, while my scale tells me I am getting heavier? It's not muscle mass.

More often than not, I go over my daily kcals by a few hundred, and really all I want is a chart that can track these overages, or "caloric balance (calories over)" charted over time.

Thanks!