Hi Chalmers,
It seems those could be digitizer lines from a low quality digitizer panel — and if it has never surfaced before in the forums, perhaps Chuwi has opted to change their supplier for the Chuwi Hi12 digitizers yet again.
May I ask for your serial number as that may be significant to identify the batch affected?
See: https://www.reddit.com/r/ipad/comments/3rdju0/my_replacement_digitizer_has_weird_lines_and/
Another remote possibility is the lines were somehow imprinted superficially on the display (clearly not at a depth beneath the glass) during production/ packaging. In that case you could consider a careful solvent wipe, not just water or soap as they may be insufficient to remove rubbery/sticky/stubborn oil stains — just make sure the solvent doesn’t damage the screen.