I believe AAC in post #19 refers to the AAC in post #1. It is generally better than MP3 at the same bitrate. A form of AAC is actually used in digital TV broadcast in some countries. Its use is not restricted to Apple. (Unlike ALAC, I do not see a good reason to use it outside Apple ecosystem.)
AAC is indeed available from Tidal under one of the following conditions:
1. You (accidentally) got a lossy (Premium) instead of the lossless (HiFi) subscription from Tidal. I have seen this a few times. I blame this on marketing. "Premium" actually means "worst".
2. You set Tidal quality to something below HiFi
3. The album you chose is really not available in lossless quality. However, Tidal often has duplicate versions of the same album. You should try them all, to reiterate my point 2d in post #2.
AAC is indeed available from Tidal under one of the following conditions:
1. You (accidentally) got a lossy (Premium) instead of the lossless (HiFi) subscription from Tidal. I have seen this a few times. I blame this on marketing. "Premium" actually means "worst".
2. You set Tidal quality to something below HiFi
3. The album you chose is really not available in lossless quality. However, Tidal often has duplicate versions of the same album. You should try them all, to reiterate my point 2d in post #2.