connectivity via Bluetooth with my OnePlus Nord 1

During the installation, the Garmin connect app advised me about connectivity issues with my phone (even though no issue with oneplus mentioned in the manual). 

My biggest trouble is when my earphones are connected to my phone and I'm using my watch to find the phone it rings in my earphones (why?) BUT when I answer incoming calls they are delivered to my watch or sometimes to my phone and never to my earphones (should be the default) -it is very frustrating. I can’t control phone function such as Spotify with my watch or any control over my phone. Of course the Spotify installed works fine but has nothing to do with the one on the phone. Sometimes It deletes the sleeping record, or don’t score it at all or thinks I’m climbing stairs while driving my car up a hill. Anyway my most pressing issue make it connect correctly with the BT on my phone.

Operating system OXYGEN OS

as for the watch, I did the update today 11/05/22 so what ever that means.