(Inofficial response, feel free to correct me or to ask to delete that response if it is not necessary)
When was the last time you’ve seen your pixel art undamaged?
When did you encounter that your pixel art was griefed?
If we know this two times the grief happened between those two times
It was fine yesterday (and possibly early this morning) and it was broken today, but moderators can see who edited a tile, so they already know who broke it.