Earlier quoted context omitted.
base64 inline your image with the HTML and you should be well past that threshold. It's preferable to not make additional requests (like for an image) on an error page - in case the requested server is at fault - breaking the error page.
Fun fact: did you know you can inline an image without base64 encoding it? Use svg you can inline the markup using a data url without base64 encoding. This is how I do my favicons at simpatico[0]: " > What's nice is that this opens up the possibility to generate dynamic favicons really easily using only string interpolation. 0 - https://simpatico.io/svg.md
Thanks for the tip, and the many examples on your site!