Very high kilometers in first second of run

I quite often have an issue where the first second of a run will have a very high number of kilometers.

I know the first instinct will be to blame my phone's GPS, but I know that's not the case because I use Strava at the same time and it's using the same phone GPS. I wait for Strava to get a GPS fix, start that, then start my Garmin.

The map is correct.

It's a Vivosmart 5.

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