I've had my garmin Fenix 8 for a year and every activity had a reasonable callory burn statistic u till today.
After 23 minutes of swimming it says Ive burned 2000+ calories.
All my user data is correct. This happened overnight without me chaging anything.
What could be the issue?
In my 'active calories' tab, it shows an accurate estimate of calories burned after the swim. (300). 
