Glitch.
Try to not delete anything, as annoying as it sounds.

Also, try to do a search next time. This has been asked many times.

Hmmm. i got that. It seems to have gone way now. I suggest you wait, as annoying as it sounds :/

Just a glitch, in fact that's not even a new glitch, it just keeps on coming back ... The only thing I used to do when I used to get this happening to me years back was either delete the comments from the new image after submitting it and before it's activated (to avoid confusion altogether from other members as they can't see it before activation) or just delete them from the old image before deleting the actual image itself, which actually does stop them from showing on the new submission. (either way the only way to get rid of them is personal deletion which can take some time if you get a lot of comments)
*it happens with character links too, which can be a hassle... as mods don't activate incorrect character symbols, I know it isn't always the best option or anything but maybe it'd be easier to not delete the image in the first place and just leave it so you don't have to worry about checking the image after submission every time*

Yes that is a glitch, but I wouldn't bother reporting it, Steet doesn't bother anymore. This happens when you delete a previous drawing.