I've identified the Garmin Connect app as being the culprit of severe battery drain on my Sony Xperia X Compact.
A search tells me this issue has been raised on this forum before, but not for a couple of years.
I recently updated the software but this did not fix the problem.
Does the app have to be running for notifications on the watch to work or can I just keep killing the app when I don't need it to sync?
I have a vivomove HR if that makes a difference.