I wonder why the phone or watch would be vibrating or lighting up on connection or disconnection. My watch switches connection several times each day between iPhone and iPad, depending on where I am. But I never notice that or even be notified in any way.
The same with other Bluetooth devices: the phone doesn’t do anything visible in connection or disconnection.
In case you didn’t manage to find a solution yet, here’s how I solved the issue on my Garmin Forerunner 235. On your watch, press the “activity” button on the top right corner and browse the menu using “up” and “down” buttons to go to “settings”. Then, go to “Bluetooth” settings and browse to “connection alert”. Turn this off and you shall be able to get rid of the constant pings about watch connecting or disconnecting to your mobile phone.
Thanks so much! ... and my dog thanks you even more....every.damn.night!