Do note that heatmaps are affected by the humidity values as well as the "density" of data collected. Since from the trajectory mapper we can see that more data is collected in some areas than others, it follows that some error in the result can be expected.
Moreover, it is recommended to partition the data into boundaries. By averaging values in set boundaries, a choropleth map can be used instead of a heatmap. A choropleth map is more appropriate in this case.