This is related to the widely discussed issue about the voice prompts for turns when using navigation that can't be disabled.
The currently recommended workaround is to disable turn alerts on the watch, which stops any kind of turn alerts including beeps and vibration.
However what I observed is that even with turn alerts disabled, there are still voice prompts for upcoming course points. There are two voice prompt per course points - a short distance before when approaching a course point and then another voice prompt right at course point. Just to be clear, this issue applies to custom course points on the course, such as checkpoint, summit, aid station, etc. For example, it would say "Summit in 121 feet" or "Point in 247 feet".
These prompts come out of my phone speaker, and as far as I can tell, there is absolutely no way to disable them unless I turn Bluetooth off on my watch. But disabling Bluetooth would also disable Live Tracking, so that isn't a good solution.
I wanted to mention this as a separate issue so that it doesn't get overlooked.
FYI: Garmin-Laurie