Hi Marya, I may have an answer but it's only a possibility. I'm not affiliated with Medium so I can't confirm if this is true.

However, I took a look through your stories and saw you used an image from Flickr.com. Images there are not copyright free like pictures on Unsplash or Pixabay. People must have explicit permission from the image owner to use it from Flickr, unless it's labelled as Creative Commons. By default, Flickr sets images as All Rights Reserved. Medium takes copyright use pretty strictly.

It sucks and I'm sorry you were revoked. It would be much better if a warning was given with the reason and time given to fix whatever the issue flagged was.