this is the best plausible reason for why the file size differs. I've also noticed some unepxected media restoration (thought I cropped/edited a video, it is still there in full length and resolution).
This also helps explain why my iPhone storage always seems to be at its limits, despite my obsessive management.
> thought I cropped/edited a video, it is still there in full length and resolution
It's been possible to create a clip from a video file that merely changes what parts of the video are displayed without effecting the data in the original since the Classic Mac OS days.
If you want to completely remove unwanted portions of a video to reduce the size without a loss of quality, there are many options. LosslessCut is a cross platform option that is both free and open source.
This also helps explain why my iPhone storage always seems to be at its limits, despite my obsessive management.
Anyway, we all know foss unix ftw :P