I have a FR 935 which was recently updated to 13:30. I wear my watch 24/7, and previously RHR was calculated as an average of all readings during sleep, as documented here: https://support.garmin.com/en-GB/?faq=F8YKCB4CJd5PG0DR9ICV3A
However, the last 2 days calculations have started out "normal" (around 60), but at some point during the day, dropped to the essentially the lowest HR reading during the day (around 53). Which is actually what I prefer.
Anyone else experiencing this ?