Open-water swim distance differs from the track recorded? (Todays swimrun 352m vs. approx 750m, unacceptable)

Hi,

Did my first open-water swim today with 955. Track looks nice and smooth, but the distance is something that makes me think.

Garmin Connect reports 3810m: https://connect.garmin.com/modern/activity/9055012148 

Opened the GPX in GPXSee as wanted to have a little bit closed look and it looked like it's 4k. Umm. Upload GPX to some online tool:


What are others seeing as open-water swim distance? Does it differ from the GPX track? 

Does anyone have any ideas/explanations to give?

Here is the exported GPX if someone wants to analyze it.
activity_9055012148.zip

EDIT: Apparently this was just a mild issue compared to todays one. Link to it: https://forums.garmin.com/sports-fitness/running-multisport/f/forerunner-955-series/298162/open-water-swim-distance-differs-from-the-track-recorded/1443414#1443414