In case you missed it, Facebook announced a short while ago that they are limiting the amount of text in images used in advertising to 20% of the image.Now, if you place an ad on Facebook that includes an image with more than 20% of it covered in text, it will be rejected (and yes, Facebook is actually enforcing their rule this time).
Side note: This 20% rule appears to go for all images in an ad. I recently tried to promote a link page post and it was rejected because the feature image that was pulled from the link had too much text. I also had a client's sponsored page ad rejected because their thumbnail (their logo) had too much text in it. Seriously Facebook???
Facebook also restricts cover photos to 20% text as well.
Anyways, here is a handy template infographic from Facebook appmaker, Shortstack, that will help you figure out what is and isn't too much text in an image for Facebook's liking. Hopefully this will save you some of the frustration that the rest of us have had to endure as we all adapt to yet another Facebook change.