Mobile phone photos are usually saves as JPEG images, and are 8-bit captures (as opposed to raw images from a dSLR, for instance). Whenever you add too many filters to such images, you’ll start to see processing artifacts. Some filters are more prone to causing artifacts than others (equalize, in particular), and in general, the more extreme the effect, and the more contrast the filter adds, the greater chance you’ll see processing artifacts. To avoid this, try using fewer filters, or try to achieve the look you want with a different set of filters.