I see a JPG format image is used. It is not comfortable for all major browsers. Choose ICO, PNG or GIF image. ICO is recommended. You can use this free software to create one.
I have a related question. The favicon showing up for me is a super-old one that I may have uploaded via FTP many years ago. How do I change it? Is there a way to see how the current favicon I have got there? Thank you! My site: http://theartofapplying.com