I've seen this one before. A minor character in "The Diamond Age" (1996) by Neal Stephenson, got virused in his implant. He had pop up ads in Thai (which he did not understand) over half his visual field 24/7 until he committed suicide to get away from them.

A more realistic downside: this program which has given some vision to blind people. A very good thing as such, but IIRC at one point there was discussion about shutting it down. Which would put the blind patients back where they started. (I welcome correction, as my Google fu is not finding that detail today.)