We are not changing the exposure on a sequence. We keep the same exposure during the transit. So it's important to be aware of the starting point and the variation on air mass during the session.
Regarding the 3D / star tool.... it's a pretty tool almost unusable to analyse stars on smaller computers (like a raspbery pi). To loot at the saturation, you only need the peak value. If you want to show a graph, It will be infinitely more useful a simple 2D cut through the centroid of the brighter star inside the selected region. This will be easier to interpret that a full 3D graph that you need to rotate: you will see immediately if you have reached the saturation point (star profile flattened on top) of ir the maximum is only a hot pixel and you still have room for more exposure.