Similar to what @KW was experiencing here: https://support.mozilla.org/en-US/questions/1392858 I'm also having the same issue. I tried replying to that thread, but it's been archived. I have two printers that were removed from macOS System Settings in Sonoma 14.5. They are showing in the print dialogue menu in Firefox 127.0.2 on both my laptop (MacBook Air M1) and desktop (Mac Studio). Rebooting the computer, restarting Firefox, etc. haven't resolved the issue.