Spotify streams all music at 160kbps OGG for free users by default, so that’s what this archive is dumped at - the original Spotify content, no transcode. The only difference is they re-encoded all the songs with a ‘popularity’ of zero at a lower bitrate, because that saved an enormous amount of data for all the AI crap pumped into Spotify that nobody listens to.

Side note - it would probably not be possible to do a dump as a paid used (as they would notice a user account is being abused, and ban it), but paid accounts go up to 320kbps OGG and some content is also available lossless (as FLAC).

Anyway, 99%+ of people can’t consistently tell the difference between a 160kbps OGG and lossless, because of limitations in either their equipment, training, ears, or a combination thereof. This has been blind tested many times and the audiophiles that ‘swear they can tell’ are always proven wrong, they then usually blame the equipment or test. There’s tests you can run yourself too, eg here: https://abx.digitalfeed.net/list.html