I have done this: take the lowest bitrate MP3 file (like 128 kbps) and use an audio converter software to “upscale” to the highest quality audio file (I think 192kHz/24bit) and my Yamaha will read the file as “192kHz/24bit”. So it’s a fake 192kHz/24bit file.
They do the same thing with video resolution - take 720p and 1080p and upscale them to 4K resolution. So it’s fake 4K.
I think they do the same with some Atmos and DTSX files - many of them don’t sound very active because they’re fake.
Since Spotify does not claim CD quality, you can’t sue them just for upscaling the files.
Just like how Netflix doesn’t claim that their 4K files are “True 4K” and Atmos files are “True Atmos”.