Same issue with OnePlus Nord 2 as well. Just to be very clear - I have CMF Buds Pro and CMF Buds (the non pro). And when any of these are connected with Samsung, iPhone or MI phones, it works fine. But when you connect any of these 2 buds with OnePlus devices, volume remains frustratingly low. So I’ve tried not one, multiple buds with multiple phones, but these behave very weirdly.