lilac grotto
If you have enough bandwidth, you can increase your bitrate. Higher bitrate means better image quality.
And, more bandwidth usage, means more packet loss and lag in case someone else in your local network uses your bandwidth for other stuff, like Netflix, YouTube, downloads, etc.
Also, if it's available for your current setup, you should see the upscaling feature in GFN app settings. Feel free to try some upscaling features and see how it will improve in your case.