I noticed that sometimes when I try to post plants in signatures that some of them have a colorful background. Those that were not affected are from 2017, whereas the images that are affected are older like from 2012-2014. My mistake, I also found some from 2017-18 that are affected as well, seems to be random which ones are without background.
This is only a problem when I try to post the images in my signature at dragon cave, here on flower game it looks fine.