Some more recent bluetooth codecs (such as LDAC or aptX) are better ahead in audio compression, which given bluetooth's limited bandwidth (and given than higher bandwidth usage means also more battery consumption), is something to keep in mind at all stages. In general, bluetooth audio quality is quite a mess of codec negotiations that happen mostly transparently to the user when an earphone connects. When a call is placed and the headset needs to also send audio besides receiving it, further codec changes are negotiated on the spot, prioritizing latency vs quality. Here's a quick (kinda) guide to the most common bluetooth codecs any given audio device might use: https://www.whathifi.com/advice/what-are-the-best-bluetooth-codecs-aptx-aac-ldac-and-more-explained