If the image you want to use for a Facebook ad has some text on it, I recommend you use Facebook text overlay tool to check if the image is OK for Facebook ad or not.
The tool simply allows you to upload an image to determine how much text is in your ad image.
If the the proportion of text to image is OK, your ad will run normally. If the proportion of text to image is too high, your ads may not run.
Below is a screenshot of a test I carried our recently :