I think ever since spotify implented the feature where you can décidé which bluetooth device should be used to play music through, 

My phone has been having buggy bluetoorh connection with spotify. 85% of the time it works fine.

But then often the connection stops being stable, and android keeps connecting and disconnecting to my bluetooth speakers or earbuds.

Or android simply doesnt recognize my bluetooth device at all anymore... 

until i force quit spotify and then android recognizes my device and connects to it immediately.

Poco x3,

have had thiz problem since at least MIUI 12.5... on all versions.

but it started with the spotify update that allowed bluetooth device to be selected. 

tried many different android versions and factory resets etc.It's caused by spotify