I tried what you asked, there were no active connections but I checked, the icon was already grayed out, set "make connectable = no", reverified the grayed out icon, went back to the initial clock screen and reconnected without any problems from chrome.
I confirm that setting "make connectable = no" with an active connection breaks my connection.
I previously used Garmin because it's one of the few that allows you to disconnect bluetooth and "turn it into an offline device."
I am trying to achieve this same result, it's not important to me how.
If by disabling bluetooth I also cut off connections even better.
Is it possible that there is some scheduling that reactivates bluetooth after a while?
Or by going into the settings or trivially by unlocking the device?