I regret not keeping track of them all now but there are some cases where I notice the thumbnail appears to be slightly corrupted, e.g. the far right observation here:
I used to get this problem (but black, not radioactive purple!) a lot when I was on my win95 antique. Ended up buying a new computer because it was so deathly slow at everything, and now I rarely encounter it. Back then, it would show some images corrupted, but for other people it showed the same images just fine.
On this occassion (your example above) I see the same as you all do…
Has someone tried the option of ::
Repair broken URLs - I dont think this will work (otherwise I would just have done it), but it might just result in the small, medium and large pictures being reconstructed from the original?
The other option is to flag the picture - on the picture page https://www.inaturalist.org/photos/3852514?size=large - and ask for it to be reconstructed from the original, although I dont suspect that there is an automatic workflow for that.
It appears to me that the medium sized ‘thumbnail’ https://static.inaturalist.org/photos/3851597/medium.jpg is the only version corrupted. The square, small, large and original versions look fine. So presumably something glitched as it was creating the meduim.jpg thumbnail. Simplest cure would be to delete and re-add the photo and it will regenerate thumbnails for it (simplest assuming you are the owner of the observation, otherwise it would have to be a back-end admin action to force it to be regenerated).
Assuming the image looks fine before you upload it, my guess is that this is an intermittent issue in photo processing on our end. However, if anyone has an image for which this happens consistently please send us the original file so we can try and replicate the issue. Not entirely sure what to do about the intermittent issue, though. We are considering switching to dynamic image resizing some time this year, which would remove the need to process photos like this, but that’s still a ways off.