When playing the same song with same DSP settings and MQA… The signal on the one hooked up the Onyx says “Enhanced” while the other one says “High Quality”
As @Derek_Wyman mentioned, there have been some reported issues with hi-res chromecast playback and Google is aware of this fact but there have been no new updates recently. You can follow the main thread here (Chromecast Audio dropouts).
As for your question regarding Enhanced vs High Quality, I would need to see the Signal Path screenshots to make a conclusion regarding that question.
I think if you adjust the volume on the CCA it will drop you to “high quality”. If you pass through at 100% volume you should see lossless or enhanced (depending on any DSPs