i just tested it on a higher resolution photo (original: 4.7MB) and, while the result was slightly downsized and compressed (uploaded image size: 0.97MB), I didn't see any artefacts or noticeable degradations of quality. Also tested it with a smaller resolution image and didn't see any difference, either.
Some users have reported a similar issue in the past, and our best guess is that Imgur is possibly doing some A/B testing on reducing anonymous image upload sizes and it's being too aggressive in some situations.
Until reddit makes its i.redd.it image hosting service available for third-party apps to use, Imgur is all we really have; if it's producing bad uploads for you through RiF, you'll have to upload the image to Imgur or another image host, manually. Lucky Patcher Kodi nox