I expect some compression, but it's really bad with a mostly polished clip.
This doesn't sound like typical hosting file compression or lower quality mp3 format, it actually sounds like a big slathering of audio compression on top of what has already been compressed/limited.
Interesting thing is I didn't notice it until I started really polishing my clips (recently, with my Apollo acquisition).
Years before, no problem - but I did a very basic limiter setup.
So, I either gotta not polish my clips (not bloody likely), or go for a lower LUFS when limiting.