It's nearly lossess if you can connect and maintain a 990kbps connection, but it still doesn't have enough bandwidth to do it truly lossless. I think it would require 1411kpbs to be actually lossless. It is still better than any codec I know of for bluetooth as far as that does, but bluetooth just kinda sucks for that sort of application.

FLAC is a lossless compression format. It will reduce file size but keeps the audio quality. So-called "high-res" format on streaming platform like spotify (mandatory fuck spotify here) are usually mp3 320kbps so heavily compressed and lossy, indeed.