I don’t think this is citra but it is very annoying All the data for Ultra Sun/Moon second screen plus the box around the text. Here is a screen shot
First update Citra to the latest version which right now is Canary 1956 or Nightly 1696. Next make sure that you are on the latest drivers for your GPU.
If you still encounter the issue please upload your log file and fill the template below.
This won’t help them. They’re having an iGPU/driver issue. But we need a log file to see which it is. This is why we want people to fill out the support template. It prevents having to ask for the information again later.