it depends on the sense of the phase, broken image for me it's kind of something that denigrate the reputation of someone in Portuguese... like : Perda de credibilidade

In Brazilian Portuguese we don't have an exactly match for "broken text/image". You can say there are missing letters or the image didn't loaded properly, or the image didn't came. There are missing letters = Tem letras faltando. (if there are squares, question marks or whatever) The image didn't loaded/came = A imagem não carregou/veio. (if you can't see the image) If you wanna go full informal, you could use the words we usually borrow from english: The text/image bugged out = O texto/imagem bugou; (if there are glitches, overlays or any weird behavior)