Hey @FazedYT, thanks for joining us on the Dropbox Community.
Generally, Dropbox does not alter the files you add to your account in any way.
The previews of your files on the mobile app or website might not be in the actual quality, as they would if they were downloaded and opened locally, but the actual file doesn't change.
Can you walk me through the steps you followed to download the file from Dropbox to your phone?
And can you please send me a screenshot showing this discrepancy?
Thanks!