Does dpreview gallery recompress photos?

Hi, i'm testing the dpreview gallery feature, I uploaded few photos at max resolution allowed (1600 horizontal) then zoomed on detail and compared to original jpg I uploaded. I can see image has same size but more pixelization, like if the original jpg was heavily recompressed.

Does anybody know if there is a way to keep uploaded jpgs most faithful possible to the ones uploaded ?

Samples from reviews don't seem so heavily compressed so maybe there is a parameter?

Thank you
Antonio