icloud.com downloading unmodified version is not giving me the best quality

Hello,

I have an issue to download via browser from icloud.com umodified version of a video that I have in my icloud.

Original version has more than 1GB, but when I download it using unmodified version it downloads a video of 82MB!!! I tried different browsers, different options but still the video has only 82MB.

Any idea why?