UPDATE: SoundCloud has responded to the reports of lower sound quality and claims that these codecs and others have been in use since at least 2016. Read their full response here.
Audiophiles beware, SoundCloud has dropped its audio quality from an already paltry 128kbps to a new low of 64kbps Opus. For non-audiophiles, a bitrate of 64kbps Opus is supposed to sound as good if not better than 128kbps MP3, but due to an older codec, the end result leaves the current audio quality of Soundcloud far below what it had been previously – which already wasn’t fantastic.
SoundCloud has yet to comment on why it’s cut the bitrate on its platform, but there are already plugins for various browsers that will help you restore the audio quality back to 128kbps. 
https://twitter.com/DirectOfficial/status/948584457405128704
H/T: Pigeons & Planes
Is this only when you stream music via their website or does this include mp3 files downloaded off their website?