The translators do that cuz this is an agregator site.
They upload previews of their chaps that they worked on early which they know sites will take and upload without their permission. Then after some time release the actual copy later ~with the intention that you go to thier official outlet and read it their and possibly give them a little thank u for making these more widely available.
If agregator sites just gave them their props and didnt make it so easy for authors to sue translators for helping fans access* their work they wouldnt have to do that.