You cannot compare kbps numbers of files encoded with different codecs and make assumptions on quality.
Each codec is able to compress differently good, so a 64kbps in opus sounds much better than 64kbps in mp3, for instance. 128 kbps in opus for stereo is plenty, quasi-lossless, while on other formats it is pretty bad.
Bluetooth is pretty lossy unless you are using LDAC. That said so is a 128k or 64k music file. LDAC is 990kbps
You cannot compare kbps numbers of files encoded with different codecs and make assumptions on quality.
Each codec is able to compress differently good, so a 64kbps in opus sounds much better than 64kbps in mp3, for instance. 128 kbps in opus for stereo is plenty, quasi-lossless, while on other formats it is pretty bad.