Downloaded data.csv does not seem to be correct

Downloading data to a csv file does not seem to be correct.

- Plotting the downloaded data results to a graph slightly different than the one shown the UAV Log Viewer. See two graphs below.

**UAV Log Viewer plot**

**Using Excel to plot the downloaded data**

- Downloading the data with mavlogdump.py results to slightly different dataset.

**Discuss thread:** https://discuss.ardupilot.org/t/uav-log-viewer-downloaded-data-csv-problem/116881
**Tested Flight log:** https://drive.google.com/file/d/13SzHmCFXVaDOSkUoY7rSCYr1NIuQwrz_/view?usp=sharing

Reproduce the discrepancy using the linked tested flight log, then compare the UAV Log Viewer CSV with the graph and the output from mavlogdump.py. Done means the downloaded dataset produces the same plot and values as the viewer, or the remaining difference is explained.

Written by the indexing model from the issue text.