The pic I post on the site has a different md5 from the original pic on my disk, but the png pic is ok. Maybe something wrong?

Just like:
5e94898d72b5a7103896457b5aae59dd *43507686[97978585].jpg
9387b940c7cd92564fdcbeda5fae967a *yande.re 304337 tagme.jpg

Yande.re will delete some metadata like Exif when uploading.

The size changed too, prefer keeping the original files though.

We implemented that measure to avoid retaliation on contributors from Animepaper. Now that it-s gone I wonder if we still need such feature.

blooregardo said:
We implemented that measure to avoid retaliation on contributors from Animepaper. Now that it-s gone I wonder if we still need such feature.

good point, I'll remove it if it not needed anymore.

Personally I would leave it in place. Other sites might be watermarking scans.