While we're waiting for the developers and/or Google to provide the software fix that will allow us to use our Galaxy watches in the manner for which they were created, I've found a way to halt the constant notifications about the plug-in having stopped working.
Turn your watch off. Take it off your arm. Set it on your desk (or any other place you find appropriate).
The notifications stop. Problem solved. Start working it "old school", and look at your phone often to see if there are any important notifications you might have missed. 😉