I was thinking the same as @Peedyex Depends how long you’ve had the dashcam and size of memory card in it. Any shocks it gets from slamming a door could cause that bit of footage to get saved as it thinks its been in a bump so what was a 2 hour memory card could be down to a 30 minute card until you delete those files.
Strange how immediately after the incident is there but not the previous 45 mins… is there anything there from before before that 45 minute period?
Was the camera on? Not the first time mines has been unplugged by a garage or me to plug in a tyre inflator, or just bumped and the wire has been loose and I’ve not noticed 🫣