Oh no. Tried to boost a post a got the dreaded “Your Post’s Image Uses Too Much Text” message? (See below)
Facebook has a policy on the amount of text in a image post. For usual image posts on your timeline – fine, but once you boost the post image, if the image contains too much text Facebook doesn’t like it.
Facebook used to have the 20% rule being not more than 20% of the image can contain text. Now they do allow a bit more (being not as strict) but they penalise you by limiting your reach.
The best thing to do is really make sure what ever text you have in your boosted post image is punchy and to the point.