Here are some example images that got inverted/outlined/line-patterned when uploaded. I tried uploading newly created pngs, editing pngs, and old pngs downloaded from the internet a year ago.
I thought so too until near the bottom of the thread, people started posting messed up pngs with very strange artefacts. So not the same symptoms, but more. It’s something the devs changed recently…
Edit: Oh you said the pixelfix thread. Sorry I looked at the other thread. Yea idk what pixelfix was linked for.