Just for readers finding this later:
The issue seems to be caused by extra QuickTime TC and meta tracks the Gopros series 5 and 6 burn into the MP4 clips; in these tracks special telemetry data are contained like speed, height, GPS coordinates, etc.
Kodi 18 (Leia) has already changes regarding this, see also Issues · xbmc/xbmc · GitHub.
2021-01-16: New kodi tracking, actual link is https://github.com/xbmc/xbmc/pull/12579.