There are many reports at the Google AdSense Help forum with publishers complaining that Google is displaying weird characters on their ads. Here is a picture of one:
Here is another picture, this one is from my personal blog:
Notice the ad at the top right showing weird characters.
Google has confirmed the bug in those threads and said:
Currently, there is no ETA for when the issue will be resolved but it is good to know Google is aware of the issue and actively working on fixing it.
