kanryu
commented
3 years ago It's a really annoying story. There is nothing different about being JPEG in essence, but please do not increase the extension without permission.
However, as long as the * .jfif file actually exists and can be read as a codec, it should be supported.
Images with .jfif extension, despite this essentially just being a different variation of the file extension for jpeg/jpg, do not work in the viewer.
Windows can be configured to save all jpg files as jfif. Recently this was set on my computer, not sure if it was by windows update or something else. However if windows is being reconfigured to save as JFIF extension by default, this would be high priority to fix.