A lot of those BT adapters are cheap shit. Like the aforementioned RTL8821CE: it’s a nasty hack to do wifi and BT using a single 2.4 GHz transponder. But here’s the thing: however bad they are, they’re made to work well in Windows - possibly with a lot of awful engineering shortcuts and hackery, but in the end, Windows users will never know and that’s the point.

When open-source developers try to make equivalent Linux drivers without documentation or help from the manufacturer, reverse-engineering their way around the general crappiness of the products, you get… well, not very good drivers. And it really is nobody’s fault but the unhelpful adapter’s manufacturer.

So there is that, and the general bugginess on BlueZ on top of it.